Xvid - "rough cut", still some FX and fixes that needed to be done.

DVD5 - "first release", all FX done, full menus, bonus features

DVD9 - "final release", same as DVD5 plus some more bonus features, better video quality

Purist - the final release with some changes undone to make it closer to the theatrical version of the film. No bonus features.

H264 - HD version but with minimal changes from the '04 official DVD - color correction and one or two minor changes.

2CD - don't know about that one.