guinea vs guinea hen

guinea and guinea hen both are nouns.

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

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

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

guinea (noun)	guinea hen (noun)
a west African bird having dark plumage mottled with white; native to Africa but raised for food in many parts of the world	female guinea fowl
a former British gold coin worth 21 shillings	flesh of a guinea fowl (especially of hens)