watcher vs spectator

watcher and spectator both are nouns.

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

As nouns, watcher and spectator are synonyms defined as:

watcher and spectator: a close observer; someone who looks at something (such as an exhibition of some kind)

Other synonyms of watcher include looker, viewer, witness.

watcher (noun)	spectator (noun)
a guard who keeps watch	a woman's pump with medium heel; usually in contrasting colors for toe and heel
a close observer; someone who looks at something (such as an exhibition of some kind)	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