repeater vs doer

repeater and doer both are nouns.

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

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

Other hypernyms of repeater include actor, worker.

repeater (noun)	doer (noun)
a firearm that can fire several rounds without reloading	a person who acts and gets things done
(electronics) electronic device that amplifies a signal before transmitting it again
a person who repeats
someone who is repeatedly arrested for criminal behavior (especially for the same criminal behavior)