brass hat vs officer

brass hat and officer both are nouns.

Word	Noun	Adjective	Verb	Adverb
brass hat	Yes	No	No	No
officer	Yes	No	Yes	No

As nouns, officer is a hypernym of brass hat; that is, officer is a word with a broader meaning than brass hat:

brass hat: a high-ranking military officer
officer: any person in the armed services who holds a position of authority or command

Other hypernyms of brass hat include military officer.

brass hat (noun)	officer (noun)
a high-ranking military officer	a member of a police force
	someone who is appointed or elected to an office and who holds a position of trust
	any person in the armed services who holds a position of authority or command
	a person authorized to serve in a position of authority on a vessel

brass hat (verb)	officer (verb)
	direct or command as an officer