applier vs doer

applier and doer both are nouns.

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

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

applier: a person who requests or seeks something such as assistance or employment or admission
doer: a person who acts and gets things done

Other hypernyms of applier include actor, worker.

applier (noun)	doer (noun)
a device for applying a substance	a person who acts and gets things done
a person who requests or seeks something such as assistance or employment or admission