grease monkey vs repairman

grease monkey and repairman both are nouns.

Word	Noun	Adjective	Verb	Adverb
grease monkey	Yes	No	No	No
repairman	Yes	No	No	No

As nouns, repairman is a hypernym of grease monkey; that is, repairman is a word with a broader meaning than grease monkey:

grease monkey: someone whose occupation is repairing and maintaining automobiles
repairman: a skilled worker whose job is to repair things

Other hypernyms of grease monkey include maintenance man, service man.

grease monkey (noun)	repairman (noun)
someone whose occupation is repairing and maintaining automobiles	a skilled worker whose job is to repair things