It seems like you can clearly delineate, by whether you are being paid to be there, or you are paying to be there.

The analogy is tough because as far as I know there isn't an official definition of what a sailor is. Nor is there an internationally recognized registry like the "Fédération Aéronautique Internationale" which keeps track of people it considers Astronauts/Cosmonauts/Taiknonauts, etc.