theatergoer vs watcher

theatergoer and watcher both are nouns.

Word	Noun	Adjective	Verb	Adverb
theatergoer	Yes	No	No	No
watcher	Yes	No	No	No

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

theatergoer: someone who attends the theater
watcher: a close observer; someone who looks at something (such as an exhibition of some kind)

Other hypernyms of theatergoer include looker, spectator, viewer, witness.

theatergoer (noun)	watcher (noun)
someone who attends the theater	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