hitman vs gunman

hitman and gunman both are nouns.

Word	Noun	Adjective	Verb	Adverb
hitman	Yes	No	No	No
gunman	Yes	No	No	No

As nouns, hitman and gunman are synonyms defined as:

Other synonyms of hitman include gun, gun for hire, gunslinger, hired gun, hit man, shooter, torpedo, triggerman.

hitman (noun)	gunman (noun)
a professional killer who uses a gun	a professional killer who uses a gun
	a person who shoots a gun (as regards their ability)