slayer vs doer

slayer and doer both are nouns.

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

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

Other hypernyms of slayer include actor, worker.

slayer (noun)	doer (noun)
someone who causes the death of a person or animal	a person who acts and gets things done