Hi!
Sonically I think there are no differences between the TI and the Snow. They have exactly the same synthesis features, so they can create and share exactly the same sounds.
The difference is that the TI uses two DSP chips, and the Snow has one DSP chip, so the TI will have more polyphony than the Snow, and I think the TI can be 16-part multi-timbral while the Snow can be just 4-part multi-timbral.
So basically they are identical, but the TI just has more horse-power.
Other obvious differences include the user interface, and the Snow has two analog outputs as opposed to the TI's six. However, I believe the Snow will have 3 x stereo USB-based audio outputs, for a total of 4 x stereo outputs (1 via analog out, and 3 via USB). However, I think TI OS v2.7 will also give the TI 3 x stereo outputs via USB too, so the TI will have 6 stereo outs in total (3 x analog, and 3 x USB).
More specifications on the Snow, though, can be found in this thread:
http://infekted.org/virus/showthread.php?t=29393