very different? 60 doesn't have a waveform view. You have to do it by adjusting vaguely defined parameters like "time." Though I assume 1 time=1 millisecond. The 60 was the first MPC so it's the least evolved of all of them. the 2000 is from '97 while the 60 is from '88. Think about how much computers changed over those 9 years and that's pretty much the difference, faster, prettier. Thankfully, these advances don't necessarily result in a better end product because we also found out how to make computers much CHEAPER in those 9 years.
The only thing I really like about the 2000 is the jog wheel (the wheel outside the main wheel). It makes cutting samples very easy. Otherwise it feels like a toy compared to the 60 which feels like military standard issue.
I would say go with the 60 if you're already experienced with drum machines/sampling etc. especially if already have another sampler that you know how to use. If you're just starting, get the 2000 it's much easier for beginners.