I have submitted a Schengen visa application, where my duration of intended stay is 7 days.
Now, what could be my duration of visa validity 7 days or 90 days?
No they are not the same. The period of validity is defines when you can use your visa and the duration of stay determines how long you can stay in the Schengen area during this period of validity. Therefore, it's not unusual for the period of validity to be longer than the duration of stay, giving you a bit of flexibility to postpone or advance your trip (but not to stay much longer than originally planned).
The opposite, a period of validity shorter than the duration of stay, does not make sense (it's not explicitly forbidden anywhere but it should not happen) as you must leave the Schengen area before the expiry of your visa (or secure another title to stay). Furthermore, the duration of stay for a regular Schengen visa should be at most 90 days but the period of validity can be much longer (up to 5 years).
So you might very well get a visa that's only valid for the dates you put on the application or luck out and get more than what you asked but there is no reason for the period of validity to be 90 days. In principle, what you should get is a visa with a 7-day maximum duration of stay over a two weeks period or something like that (that's what's recommended by the EU commission, even if consulates are legally free to issue something else and actual practice varies from place to place).
Duration of stay is how long you intend to say in the Schengen area.
Visa validity is the date after which your visa is no longer valid for entry or stay in the Schengen area.
To give you an example; you intend to visit Berlin for 2 weeks - so 14 days is your duration of stay. You apply for this in your visa application today, June 7th.
The visa you get on June 17th expires on November 16th. So the duration of the visa is 5 months, even though your duration of stay is only 14 days.
Assuming you get this visa, it will most likely be multiple entry so you can visit again till the visa expires.
The maximum duration of stay is 90 days, and you cannot repeat this within a 180 day period.
The visa that is stamped on your passport states both the duration of stay, and the expiry dates.
Thank you for your interest in this question.
Because it has attracted low-quality or spam answers that had to be removed, posting an answer now requires 10 reputation on this site (the association bonus does not count).
Would you like to answer one of these unanswered questions instead?