broody hen vs brood hen

broody hen and brood hen both are nouns.

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

As nouns, broody hen and brood hen are synonyms defined as:

Other synonyms of broody hen include broody, setting hen, sitter.

broody hen (noun)	brood hen (noun)
a domestic hen ready to brood	a domestic hen ready to brood