busy bee vs worker

busy bee and worker both are nouns.

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

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

Other hypernyms of busy bee include actor, doer.

busy bee (noun)	worker (noun)
an alert and energetic person	sterile member of a colony of social insects that forages for food and cares for the larvae
	a person who works at a specific occupation
	a member of the working class (not necessarily employed)
	a person who acts and gets things done