User blog comment:Brodie-001/Halo Pics for all!/@comment-34951715-20180320214802/@comment-31940183-20180321024408

The uniforms of naval officers in Halo 2 Anniversary are not specific to rank. They're all the same generic dress suit. There isn't any specific type.

And O-1 and O-2 (I think that's what you're referring to), naval ranks, Ensign and Lieutenant Junior Grade? Again, there isn't anything specific.