butternut vs edible nut

butternut and edible nut both are nouns.

Word	Noun	Adjective	Verb	Adverb
butternut	Yes	No	No	No
edible nut	Yes	No	No	No

As nouns, edible nut is a hypernym of butternut; that is, edible nut is a word with a broader meaning than butternut:

butternut: oily egg-shaped nut of an American tree of the walnut family
edible nut: a hard-shelled seed consisting of an edible kernel or meat enclosed in a woody or leathery shell

butternut (noun)	edible nut (noun)
oily egg-shaped nut of an American tree of the walnut family	a hard-shelled seed consisting of an edible kernel or meat enclosed in a woody or leathery shell
North American walnut tree having light-brown wood and edible nuts; source of a light-brown dye