gunslinger vs gun

gunslinger and gun both are nouns.

Word	Noun	Adjective	Verb	Adverb
gunslinger	Yes	No	No	No
gun	Yes	No	Yes	No

As nouns, gunslinger and gun are synonyms defined as:

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

gunslinger (noun)	gun (noun)
a professional killer who uses a gun	the discharge of a firearm as signal or as a salute in military ceremonies
	a weapon that discharges a missile at high velocity (especially from a metal tube or barrel)
	large but transportable armament
	a hand-operated pump that resembles a pistol; forces grease into parts of a machine
	a pedal that controls the throttle valve
	a professional killer who uses a gun
	a person who shoots a gun (as regards their ability)

gunslinger (verb)	gun (verb)
	shoot with a gun