For most journeys, only one train company can cover that route, so there's no comparison involved. For your journey from London to Newcastle-upon-Tyne, the only option is to use Virgin Trains East Coast.
When there are multiple companies, you can check using "National Rail Enquiries" which can search all the companies. A good example is London-Birmingham, for which there are three options (London Midland from Euston to New Street, Chilterns from Marylebone to Moor Street and Virgin Trains West Coast from Euston to New Street).
If you search for travel today (not for any future date), and you see more than one price, all labelled as the same type of ticket (e.g. "Off-Peak" or "Anytime") then there are different companies. Click on the "other tickets" section and then click the + beside Off-Peak or Anytime hover over the word "Off-Peak" on the list that appears - you will see that some of these are "ROUTE OF TICKET ANY PERMITTED" which is a ticket that can use any company, and others are "ROUTE OF TICKET LDN MIDLAND ONLY" or "ROUTE OF TICKET CHILTERN ONLY" or "ROUTE OF TICKET VIA HIGH WYCOMBE" (these are Chilterns Trains).
The "ANY PERMITTED" ticket is the price set by the most expensive company, and then the cheaper companies will have either "(name of company) ONLY" tickets, or, if they use a different route to get there, "VIA (some station that only they go through)".
In a small number of cases when there are two routes operated by the same company, there might be two prices for the different routes. There are also a tiny handful of routes where there are no "ANY PERMITTED" tickets, but, if you're on a flexible ticket, you can buy a "change of route excess fare" for the difference in price between the routes, so if you have the more expensive flexible ticket, the change of route is free. For advance tickets, you're always tied to a particular train so routing isn't really relevant.
There are three types of tickets:
"Anytime", which allow you to take any train at all if they are ANY PERMITTED or any train with the particular operator or on the particular route if they have a restricted routing.
"Off-Peak", which allow you to take any train, except "Peak" trains. Peak trains are the most busy trains - as a rule of thumb, weekday morning trains (before about 10 am) and some weekday evening trains (particularly leaving London or Manchester in the early evening when commuters are going home). The exact rules vary from train to train, train company to train company and are altered all the time. The only ways to be sure are: if the computer ticketing will sell you an off-peak ticket for a given train, then it's off-peak, or read the relevant part of the official ticketing guide, or ask in a ticketing office (or a guard on board a train). For some journeys there are also Super Off Peak tickets, with another set of rules as to which trains they can be used on.
Given that the advantage of an Off-Peak ticket over an Advance ticket is the extra flexibility, it's worth making sure you know which trains you can and can't use it on.
Both Anytime and Off-Peak tickets can be bought at any time, including at the station directly before the train leaves. If you're travelling from a station where it's permitted to board a train without a ticket (usually because there is no ticket office, or the ticket office is unstaffed at the time of boarding), then you can buy these tickets on board train, or sometimes at the destination station.
For very short journeys, such as most commuter trains, these are the only tickets available; for longer journeys, there is a third type of ticket available:
- "Advance" tickets. These are cheaper than the two flexible ticket types, but have to be purchased in advance, no later than the day before travel. They are normally available twelve weeks before, but may be delayed if there is some uncertainty what the timetable will be twelve weeks ahead (this often applies to weekend tickets due to engineering works, and also applies more widely in the run up to the timetable changes in May and December). These tickets are attached to a reservation, and you can only travel on the train that you have the reserved seat on.
There are a number of different prices for Advance tickets on a particular train (there can be ten or more prices for some trains); the ticketing system sells the cheapest tickets until they sell out and then starts on the next-cheapest. Once all the Advance tickets are sold for a particular train, the only way to catch that train is a flexible ticket. For this reason you should always try to book as far in advance (up to the maximum of twelve weeks) as you possibly can. Unlike airline tickets, the prices will not fall closer to the time of departure, so there is never a good reason to delay purchase. If you want to see all the fares and not just the ones that are currently available (ie including those that are currently sold out), you can go to BRFares but note that this site includes fares that aren't available to the general public (e.g. staff-only fares, competition winners' fares), so it can be confusing.
Advance tickets are always singles, so if you want to go both ways, then just book two singles. Off-Peak and Anytime tickets are available in both single and return forms. The return is always cheaper than two singles, but for many long journeys the return is exactly one pound cheaper than two singles, so if you can take an Anytime Single in one direction and an Off-Peak Single in the other, then that's usually cheaper than the Anytime Return. For short journeys, there may be a Day Return ticket, which will be a lot cheaper than two singles (the minimum is 10p more than one single). These are generally only on the short journeys where Advance tickets are not available.
Single tickets are always only for the specified day (chosen when you book) but for Off-Peak and Anytime Return tickets (not Day Returns), the outward half is day you specified, and the return half is for any day within thirty days of the outward journey. This additional flexibility may make a period return better than two singles in some circumstances.
There are some unusual return tickets available, which are often very good deals, e.g. the (Virgin Trains only) Super-Off-Peak One Day Travelcard, which is a booked-Advance ticket to London combined with a (same-day) Anytime ticket back from London at about the price of two Advance tickets. This particular ticket is only available on Saturdays and Bank Holiday Mondays; train companies bring in and scrap all sorts of unusual promotional tickets all the time. Train booking systems will automatically offer you the various discounted options except for a few special deals mentioned in the footnote.
You can get an Anytime Single or Return and an Off-Peak Single or Return between any two stations on the network. These will allow you to change trains as necessary to complete your journey within the restrictions of the permitted route. If you need to change stations (as you may need to in several cities where there are multiple stations that are not connected by trains, e.g. Manchester, Glasgow, Birmingham) then non-rail transport from one station to another is not included unless specifically mentioned.
If you're changing stations within London, then your ticket should include a transfer by London Underground, but this will be specifically mentioned on the ticket - it will be marked with a † in the routing section. Most journeys can also be done avoiding London, and there are cheaper tickets with a route of "NOT LONDON" (often via Reading). Journeys involving a Thameslink train, which run straight through London, and so don't need an Underground transfer, may not be marked with the † symbol, because you don't need to use London Underground.
There are tickets that include trams to transfer stations in Manchester, and there will be for transfers in Birmingham once the tram line is completed in 2016. These mention the special transfer on the ticket.
If you're using an Advance ticket, then the Advance ticket will need to include multiple reservations, or will include an "& Connections" routing. For instance, a ticket from Birkenhead Hamilton Square to London could be an Advance via Virgin Trains & Connections, with a reservation from Liverpool Lime Street to London Euston. You can then take any reasonable train from Birkenhead Hamilton Square to Liverpool Lime Street for the connecting service. This happens when one segment of the journey is on a local service where there are no reservations available, so the ticket just lets you get any train you like.
Advance tickets that require multiple reservations are quite complicated for the train companies to set up on the ticketing system, and there are often very few or no reservations available, especially when the journey involves multiple train companies. These are journeys where splitting tickets to get a separate advance with each train company may be a significant saving. Note that if one train is late and makes you miss a connection, then you can always get on the next train, even if you have separate advance tickets - so there's no disadvantage in getting the split tickets over a single-ticket advance with multiple reservations.
There are a number of railcards. A railcard normally entitles you to a discount of around a third on most train tickets bought over the course of a year, and they cost up to £30. The four main railcards are Young Person (16-25), Senior (60 or over), Family (issued to two named adults, journeys must be a minimum of one of the named adults and one child to get discount, maximum of four adults and four children) and Two Together (two named adults, must both be travelling together to get the discount). There are also HM Forces and Disabled Person railcards.
The main restriction on most railcards is to prevent them being used for commuting to work, either by restricting them to journeys starting after 0930 on workdays or by having a minimum price (currently £12) for journeys before 0930 on workdays. The exact rules change frequently and vary from railcard to railcard, so check the individual railcard you're interested in carefully. Some railcards allow First Class, others don't - again, check.
There are also local railcards, which offer (sometimes very large) discounts to people living in particular areas on their local rail services. These are mostly in tourist areas so that the standard price can be elevated (for the tourists) while local residents can still use the rail service for a reasonable price. You have to produce evidence that you live in the right area to get one of these.
A sort-of local railcard is the Network Railcard which is for non-commuter fares in the London commuter belt, and is available to anyone, regardless of where you live. London commuter fares are normally higher (per-mile) than other fares in the UK, and the Network Railcard is intended to bring them back into line for leisure journeys.
Children (under 16) get discounted child fares, normally half the adult price. For teens under 16, it's recommended to carry some form of proof of age when travelling on a child ticket. Under fives travel for free with a fare-paying passenger, but you can't reserve them a seat (they are expected to be carried, or to travel in a cot, pram or pushchair); if you want a reservation, buy a child ticket.
When buying tickets online, you can indicate which railcard you have and it will incorporate the discounts into the prices. The ticket will indicate that it is for a passenger with a railcard, and you must have the physical railcard with you when you travel. You can buy the ticket first and the railcard later if that works out better for you.
Season tickets are available in two types: weekly (green) which do not require a photocard and period (yellow) which do require a photocard, and are available for anything from one month to 12. They are the equivalent of an unlimited number of Anytime tickets along their journey route (in either direction). The only variations are child/adult and first/standard class. For some (longer) journeys, only period seasons are available. Railcards can't be used with season tickets.
These are mainly aimed at people who regularly commute along the same line, but can be useful for some other purposes (e.g. people attending a conference who are staying in a hotel a distance away might get a season ticket; holiday makers could get a cheaper out-of-town hotel and commute in).
Where to buy from
All tickets are entered into a single booking system, which all the websites have access to; there's no price reason to choose one site over another. Some charge a booking fee, some don't, some are better about overseas purchase, some are worse, some are easier to find the cheap tickets on, etc. All tickets should be available from all ticket offices at stations, but I'd generally recommend going to a larger station if you want anything slightly complicated.
When you buy a ticket online, you can either have it posted to you in the UK, sometimes paying a fee, or you can collect it from a machine in a station (the smaller stations don't have machines). To collect a ticket, you need the credit card you used to pay for the ticket online, and the booking reference; the website should send you a booking reference. Some travel agencies have ticket-printing machines, but they will generally only print tickets that are bought through the agency, usually with a mark-up.
You can also buy tickets from a machine at a station. These machines are aimed at passengers intending to travel immediately from that station and often will only sell a small range of journeys for immediate travel. Very few will sell advance tickets. You can still use the machine to collect tickets you've bought online, though, which leaves the option of buying tickets using an app on your mobile phone while in the queue and then collecting from the machine. In theory, new purchases are only loaded to ticket machines for collection once an hour. In practice, it's usually faster than that.
Sometimes, train companies offer discounts for buying tickets for their trains from their own websites, so it's often worth checking the website for the company you're travelling on. These are the normal tickets sold elsewhere, just with an extra 10-15% knocked off. Also, some unusual ticket types are not available on all rail companies.
Footnote: unusual ticket types that exist but are hard to find on the booking systems:
- SailRail - these are discounted tickets to a station near a port are bought jointly with a ferry ticket (to Ireland, to the Isle of Man, or to various Scottish Islands). SailRail is complicated and is different for different ferry companies. Sometimes you can get a ticket from any UK station, other times only within a single company's area.
- Dutch Flyer - these are discounted tickets to Harwich that are bought jointly with a ferry ticket to Holland - they're only on Greater Anglia trains (which does include trains from London Liverpool Street)
- CIV - these are discounted flexible tickets to "London International CIV" (including a London Underground transfer if you don't arrive at St Pancras or King's Cross) that require you to have a Eurostar ticket (they don't have to be bought jointly), and which entitle you to be put on the next available Eurostar if the UK train was delayed resulting in you missing your booked Eurostar. Note that Advance CIV tickets also exist (at the regular Advance price), but can only be bought direct from Eurostar as part of a through-ticket (e.g. Manchester-Paris), whereas flexible CIV tickets are discounted versions of normal flexible tickets and can be brought from other some non-Eurostar suppliers (e.g raileasy do CIV tickets).
- Sleeper berths - there are three sleeper trains that leave London six nights a week (one to Penzance, one to Edinburgh and Glasgow, and one to the Highlands of Scotland - they don't run on Saturday nights). There are supplements required when you book to get a berth in the sleeper, and it's very easy to end up with a seat-only ticket unless you watch what you're doing.
The new Caledonian Sleeper website makes this much easier for the sleepers to Scotland, by combining the ticket and supplement into a single sale. However, note that this will not sell connecting tickets, so you need to get a ticket to/from Euston (or Watford Junction) or to/from the relevant Scottish station separately from the sleeper. Or, you can use a standard ticketing site to purchase a flexible through-ticket and buy the supplement separately from the Caledonian Sleeper site. It's no longer possible to get Advance through tickets, so I would recommend getting separate connecting Advances - the combined tickets from the Sleeper website are effectively Advances and are cheaper than a flexible ticket plus a supplement.
For the Night Riveria (the train to Cornwall), the easiest way to get tickets is to buy from Great Western Railways' website, which will allow you to get sleeper supplements more easily. You can get through-tickets with sleeper berths on this sleeper, unlike the Caledonian.
Note also that various cities have combined ticketing for buses, trams, metros and trains, so you can sometimes get a city-wide day travel card for a similar price to a simple train ticket, e.g. in London or Manchester. These "travelcards" are not shown on the normal train ticketing engines. You can buy rail tickets to stations on most non-bus city transport systems (e.g. London Underground, Manchester Metrolink; again these are notoriously difficult to find on on-line booking systems), but these only cover a single journey from the mainline station; a travelcard will normally be unlimited travel for one day. Other than London Underground, these can be difficult to get from booking systems, but the destinations do exist - you can check on BRFares to verify that the destination exists and to get the station code. You might need to go to a ticket office in a station and to be fairly insistent.
Longer distance trains usually have two classes, Standard Class (used to be known as second-class; you'll occasionally still see a number 2 on carriages) and First Class (indicated by a 1 or by a yellow stripe on the carriage). Generally speaking on longer-distance trains, Standard Class is 2+2 seating (two seats either side of the aisle) and First Class is 2+1 (two seats one side, one seat the other). This means the First Class seats are considerably wider, and you have the choice of a table for four or a table for two; Standard only offers tables for four. There is usually more legroom in First Class, and often complimentary WiFi, and complimentary tea, coffee and soft drinks. First Class carriages generally also have more power sockets than standard. Some First Class journeys may include a complimentary meal, but that's fairly unusual and mostly confined to weekday peak long-distance services (e.g. Manchester-London on Virgin or Leeds-London on Virgin East Coast both serve a cooked breakfast in the morning peak and a cooked meal in the evening peak - but at prices that can exceed £200 one way for a two hour journey). Complimentary alcoholic drinks are sometimes available on the more expensive services.
Short-distance trains (e.g. ones where advance fares are not available) are usually single class (all-standard) trains. These are generally less comfortable than long-distance trains. Most commonly, they are 2+2 seating without tables; busy commuter trains may have either 3+2 seating with the dreaded middle-seat or even longitudinal seating where the seats face the centre of the train: this provides much more standing room, while still having seats for the people who cannot stand (e.g. elderly, disabled, pregnant), and for when the train is less busy.
"Outer suburban" trains (ie the longest-distance commuter trains) in the London commuter region generally have two classes - but their First Class is normally 2+2 seating. It generally has a higher quality seat (e.g. thicker padding), more legroom and will have tables. Commuter first class is often similar in quality to long-distance standard class - in my experience most people using first on commuter trains are doing so to be certain of a seat and so to be able to work on the train rather than for the superior comfort.
Some (larger) stations have a First Class lounge, which is a waiting room with better quality seats (upholstered rather than plastic), WiFi, complimentary snacks, soft drinks and hot drinks, and sometimes the ability to purchase alcoholic drinks. They're not really a match for airline First Class lounges, but they beat the heck out of the plastic or metal seats on the rest of the station, or (Euston) having to stand while waiting. I generally prefer waiting in the on-station pub, where there is one, to the FC lounges, but if you want to work on a laptop or recharge devices, the lounges may work out better. Note that First Class lounges are operated by train operating companies, so a passenger with a ticket for one company's train might not be able to use the lounge operated by a different company - though there are lots of agreements where you can.
If you're used to flying, then First Class on (UK, but also most other countries) trains is comparable to Business Class in the air - that's true of both the seating and service on-board, and of the lounges in stations.
First Class tickets are sold in the same three categories as Standard Class tickets. They generally range from about 50% more than Standard to twice the price of Standard. Very occasionally, the cheapest Advance Standard tickets sell out and there are First Class Advance tickets cheaper than the available Standard tickets. The WiFi and tea and coffee in the station and on board train can add up to a similar price to the differential between the Standard Advance and First Class Advance ticket, so the First Class might work out as a saving if you would be buying those services anyway.
Try looking at Seat61 which has an excellent page with more information on this subject.
The Rail UK Forums have more information about fares than you will ever want to know. They also have a handy guide to the First Class lounges, which also includes tricks for getting access to them without paying for an expensive long-distance First Class ticket.
BR Fares is great for pulling out information about exactly what tickets are available, but has too much information for the novice traveller.