Must've cost a fortune to film. Per "Brother", different ships use different uniforms. The Disco Blues date back to at least the 2230s and have been seen on most ships and worn by Admirals on Starbases. The Enterprise variation first seen in Brother (possibly first glimpsed in background shots of Will You Take My Hand?) is described as newer, but apparently not a full-on replacement, similar to the DS9 jumpsuits vs. the TNG two-pieces over a hundred years later. The classic turtlenecks worn by Pike's crew in The Cage (and will be worn by Kirk's crew in WNMHGB and also the Antares crew in Charlie X) is probably an older variant used by some crews.