Yeah, really. A solid color shirt with a ribbed collar and black bell-bottom pants with black boots. The rest is trivial for the shirt and pants -- a couple of sleeve bands and a patch.
Rank designation is trivial? That's pretty much the most basic information conveyed on a military uniform. When working or combat uniforms are pared down to a minimum of insignia, the rank indicators are the last to go. All the duty uniforms used in Star Trek have indicated rank. The shirts in TWOK were clearly not to be worn alone for normal duty like the TOS ones were; in fact when Kirk and co. return from the Genesis asteroid crew members immediately help them into their uniform jackets.
The jackets are more ornate, but they have the same flap and on the same side as the field jackets in The Cage. The concepts are the same, if the executions different.
But the "Cage" jackets were not worn for shipboard duty, the TWOK ones were. The "Cage" jackets were not covered with eye-candy like the maroon ones. Enlisted personnel in TOS wore the same type of uniforms as officers, in TWOK they had a completely different style. Those are the reasons I find the TWOK uniforms so different in concept from TOS.