I think both versions are different from each other, i can tell you that Gambit doesnt have the powers he has in the 360 version, or at least they are named differently. If i were you i would get the ps2 first play that and then get the 360, that way it feels like an upgrade. I think if you go the other way you may be dissapointed.
The wii/ps2 doesnt have Iron Fist but it does have teh secret character.