I've owned both so the older one runs alot hotter (I dont like to put it on my lap), no multitouch trackpad, performance seems the same to me on both models.
That's about it but IMHO the extra $200 is worth it for the much cooler running operation + a bit more battery life (something like 20-30 minutes) + multitouch (I love the 3 finger swipe to go back and foward on safari). Also when they implement the SSE4.1 instruction sets in some applications you'll be more future proof.