undoer vs doer

undoer and doer both are nouns.

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

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

Other hypernyms of undoer include actor, worker.

undoer (noun)	doer (noun)
a person who destroys or ruins or lays waste to	a person who acts and gets things done
a person who unfastens or unwraps or opens
a seducer who ruins a woman