black walnut tree vs black walnut

black walnut tree and black walnut both are nouns.

Word	Noun	Adjective	Verb	Adverb
black walnut tree	Yes	No	No	No
black walnut	Yes	No	No	No

As nouns, black walnut tree and black walnut are synonyms defined as:

black walnut tree and black walnut: North American walnut tree with hard dark wood and edible nut

Other synonyms of black walnut tree include black hickory, Juglans nigra.

black walnut tree (noun)	black walnut (noun)
North American walnut tree with hard dark wood and edible nut	American walnut having a very hard and thick woody shell
	North American walnut tree with hard dark wood and edible nut