patroller vs watchman

patroller and watchman both are nouns.

Word	Noun	Adjective	Verb	Adverb
patroller	Yes	No	No	No
watchman	Yes	No	No	No

As nouns, watchman is a hypernym of patroller; that is, watchman is a word with a broader meaning than patroller:

patroller: someone on patrol duty; an individual or a member of a group that patrols an area
watchman: a guard who keeps watch

Other hypernyms of patroller include security guard, watcher.

patroller (noun)	watchman (noun)
someone on patrol duty; an individual or a member of a group that patrols an area	a guard who keeps watch