black hickory vs black walnut tree

black hickory and black walnut tree both are nouns.

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

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

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

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

black hickory (noun)	black walnut tree (noun)
an American hickory tree having bitter nuts	North American walnut tree with hard dark wood and edible nut
smooth-barked North American hickory with 7 to 9 leaflets bearing a hard-shelled edible nut
North American walnut tree with hard dark wood and edible nut