The original had a smaller head.
I have talked to store managers who are not fond of all the companies, not just TaylorMade, releasing equipment so fast, which often creates a glut of product in stores -- and creates the need to showcase "old" equipment from a manufacturer next to the newer stuff.
I actually think it's good for Joe Consumer that the golf companies are pumping out new stuff so often. They are improving products, however incrementally, and if you don't have to be on the cutting edge, you can get some awfully good deals on the "older" stuff.
TaylorMade's R7 Limited driver, one of the best I tried in 2008, is going for $199 in stores, less than half its retail price. You can get the original PING Rapture for $199 because a Rapture 2 is on store shelves now for more than twice the price. The new one is great, and awful long, but the original isn't bad either.
I know a lot of people are loathe to buy used golf equipment, especially drivers, because they don't know how the original operator treated the equipment. But these days, you can get new stuff at heavily discounted prices and the technology, in some cases, isn't even a year old.