[Adrynalyne]

i900--international version, not in the US. Supports GSM and GSM 3G.
i910--CDMA version of the i900. Does not support GSM, and only supports EVDO.

Differences? Not many. The i900 comes in 8 and 16gb flavors, while the i910 only 8gb. THe i900 GPS is unlocked unlike the VZW version, which rumor has it that is going to change. THe i910 has visual voice mail, and Mobile IM preinstalled. The i900 does not. THere are many ROM versions, supported and custom, out for the i900. The i910 has only one thus far. The i900 has video calling and hence a second, front-facing camera. The i910 does not. The i900 has Samsung Today 2 enabled out of the box--the i910 does not. It requires a cab install (waste of space) or a registry hack.

Thats pretty much it. I am sure there is more, but those are the most major differences.