Mr. Laser Beam wrote:
Actually, the uniforms in this movie are fairly easy to understand:
Red suit: Cadet
TOS uniform: Starfleet crew
Black uniform: Starfleet Admiral (normal)
Pike's uniform in the end scene which is the same as Kirk's admiral uniform from TMP: Starfleet Admiral (alternate, probably the full-dress variant)
I don't think that's quite correct. Pike was wearing the black uniform while he was still just a captain, and Spock was also wearing the black uniform as a lieutenant commander. I think the black uniform is for all officers assigned to Starfleet Academy as instructors and/or recruits and/or whatever else.