fastener vs doer

fastener and doer both are nouns.

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

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

Other hypernyms of fastener include actor, worker.

fastener (noun)	doer (noun)
restraint that attaches to something or holds something in place	a person who acts and gets things done
a person who fastens or makes fast