lookout man vs watcher

lookout man and watcher both are nouns.

Word	Noun	Adjective	Verb	Adverb
lookout man	Yes	No	No	No
watcher	Yes	No	No	No

As nouns, watcher is a hypernym of lookout man; that is, watcher is a word with a broader meaning than lookout man:

Other hypernyms of lookout man include security guard, watchman.

lookout man (noun)	watcher (noun)
a person employed to keep watch for some anticipated event	a guard who keeps watch
	a close observer; someone who looks at something (such as an exhibition of some kind)
	a person who keeps a devotional vigil by a sick bed or by a dead body