Interesting topic, thanks for creating it. Well there was definitely some minor and some major changes. I cannot possibly list them all, but here are few examples that pop into my mind:
- One of the earliest known public demos was played on map named DM-E3City, that featured Malcolm blasting its way through streets and completing objectives. It was basically concept for Conquest gametype that never made into final.
- WAR-OnyxCoast map was really scaled down, originally it was much larger and featured interactive objects like destroyable terrain (you can see it from UT2007 trailer).
- DM-CarbonFire was a bit different, there was a ramp leading from Shock Rifle up to catwak, the pit with UDamange and Berserk was absent, skybox was different.
- Malcolm was playable character at some point, that is proved by numerous pre-release screenshots.
- Some maps featured on pre-release screenshots never made into final game (or the maps were altered that much we cannot recognize them).
- There was supposed to be Conquest gametype that had multiple objectives and side missions, kinda mixed AS and WAR/ONS gametype. We got ONS 2.0 instead.
- Bot voice command was completely removed (or maybe it wasn't implemented at all..?). In 2005 interview with Mike Capps, he told that you could command bots by voice and they will report back current situation. It never made into retail in that form.
- Some teams from UT2004 supposed to be in UT2007, but never appeared there.