busy bee vs doer

busy bee and doer both are nouns.

Word	Noun	Adjective	Verb	Adverb
busy bee	Yes	No	No	No
doer	Yes	No	No	No

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

Other hypernyms of busy bee include actor, worker.

busy bee (noun)	doer (noun)
an alert and energetic person	a person who acts and gets things done