butternut vs butternut tree

butternut and butternut tree both are nouns.

Word	Noun	Adjective	Verb	Adverb
butternut	Yes	No	No	No
butternut tree	Yes	No	No	No

As nouns, butternut and butternut tree are synonyms defined as:

butternut and butternut tree: North American walnut tree having light-brown wood and edible nuts; source of a light-brown dye

Other synonyms of butternut include Juglans cinerea, white walnut.

butternut (noun)	butternut tree (noun)
oily egg-shaped nut of an American tree of the walnut family	North American walnut tree having light-brown wood and edible nuts; source of a light-brown dye
North American walnut tree having light-brown wood and edible nuts; source of a light-brown dye