watcher vs doer

watcher and doer both are nouns.

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

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

watcher: a person who keeps a devotional vigil by a sick bed or by a dead body
doer: a person who acts and gets things done

Other hypernyms of watcher include actor, worker.

watcher (noun)	doer (noun)
a guard who keeps watch	a person who acts and gets things done
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