crew vs ground crew

crew and ground crew both are nouns.

Word	Noun	Adjective	Verb	Adverb
crew	Yes	No	Yes	No
ground crew	Yes	No	No	No

As nouns, ground crew is a hyponym of crew; that is, ground crew is a word with a more specific, narrower meaning than crew:

crew: an organized group of workmen
ground crew: the crew of technicians and mechanics who service aircraft on the ground

Other hyponyms of crew include shift, detail, chain gang, ground-service crew, road gang, section gang, stage crew.

crew (noun)	ground crew (noun)
an organized group of workmen	the crew of technicians and mechanics who service aircraft on the ground
the men and women who man a vehicle (ship, aircraft, etc.)
the team of men or women manning a racing shell
an informal body of friends

crew (verb)	ground crew (verb)
serve as a crew member on