This page describes the difference.
Basically "miles" are the number of qualifying miles you've "flown" (where "flown" really means the distances between the airports, not what you've actually flown).
"Points" are a scaled version of Miles, where you are rewarded for buying more expensive fares (First, Business or High-end Economy fares), and penalized for buying cheap fares (low-end Economy fares).
They then use the higher of these two scales to work out your status.
eg, to get Gold status (25,000 miles or points required) you could either fly 25,000 miles in Economy Class, or you could fly 16,667 miles in Business Class, which would give you 25,001 points, or any other combination to get to 25,000 miles OR points.