No, there isn't much difference.
If you want 2000+ speeds, buy a better heatsink and run your XP 1600+ at 2000+ speeds. That's what most of us do.
At $240, the 2000+ is a ripoff when you can get a P4 1.6A for $140 and run it at 2.4GHz, or a XP 1700+ for $140 (w/ PAL8045) and run it at 2000+.