guinea hen vs guinea fowl

guinea hen and guinea fowl both are nouns.

Word	Noun	Adjective	Verb	Adverb
guinea hen	Yes	No	No	No
guinea fowl	Yes	No	No	No

As nouns, guinea fowl is a hypernym of guinea hen; that is, guinea fowl is a word with a broader meaning than guinea hen:

guinea hen: female guinea fowl
guinea fowl: a west African bird having dark plumage mottled with white; native to Africa but raised for food in many parts of the world

Other hypernyms of guinea hen include guinea, Numida meleagris.

guinea hen (noun)	guinea fowl (noun)
female guinea fowl	a west African bird having dark plumage mottled with white; native to Africa but raised for food in many parts of the world
flesh of a guinea fowl (especially of hens)