For the novice, there isn't much difference at all. You still have to learn the basics: working with imported footage, keyframing, effects, rendering, basic expressions, parenting, track mattes & transfer modes... all of which were present in AE7.
For the more advanced student, that AE 9 course would be better, as it would probably cover some of the new features in the software.
So: if you're an AE rookie on a budget and the AE 7 class is less than the AE 9 class, take it.
If you want to stay on top of the curve, take the AE 9 class.
Hope that helps.
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA