hen vs brood hen

hen and brood hen both are nouns.

Word	Noun	Adjective	Verb	Adverb
hen	Yes	No	No	No
brood hen	Yes	No	No	No

As nouns, brood hen is a hyponym of hen; that is, brood hen is a word with a more specific, narrower meaning than hen:

Other hyponyms of hen include cackler, broody, broody hen, setting hen, sitter, mother hen, layer, pullet.

hen (noun)	brood hen (noun)
adult female chicken	a domestic hen ready to brood
adult female bird
female of certain aquatic animals e.g. octopus or lobster
flesh of an older chicken suitable for stewing