middlebrow vs doer

middlebrow and doer both are nouns.

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

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

Other hypernyms of middlebrow include actor, worker.

middlebrow (noun)	doer (noun)
someone who is neither a highbrow nor a lowbrow	a person who acts and gets things done