fighter vs doer

fighter and doer both are nouns.

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

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

Other hypernyms of fighter include actor, worker.

fighter (noun)	doer (noun)
a high-speed military or naval airplane designed to destroy enemy aircraft in the air	a person who acts and gets things done
someone who fights (or is fighting)
someone who fights for a cause