they are just marine pilots if you look closely you can see they are just wearing normal marine clothes, but they have a pilot helmet that sorta looks like the odst helmet.
don't try and take a pic with pilot they don't count i read up on it and only the real ODSt count also were you gonna make a army of pilots on a island because people tried it and were told pilots aren't ODST
I didn't noticed any difference between them. I wondered why they only carried pistols. They're rubbish shots as well, so they must be marines