I think the differences can be summed up fairly simple . . .
Aside from a more powerful LS6 and bragging rights to 400+ ponies, the '02 Z06 now has the HUD, is available in Electron Blue (replacing Speedway White), has been tweaked for better ride, handling and awesome sounding exhaust.
But the real question that you need to ask, are all these changes worth $1500 more than before as far as the new car selling price?
If you decide to buy a "used" 2001, you'll likely save a bundle for the next several months. However, I seriously doubt there will be hardly any 2002 on the private seller's market until the 2003 Z06 comes out.
Let me get this one thing straight, you just turned 18, right?
Good hunting.