pignut hickory vs black hickory

pignut hickory and black hickory both are nouns.

Word	Noun	Adjective	Verb	Adverb
pignut hickory	Yes	No	No	No
black hickory	Yes	No	No	No

As nouns, pignut hickory and black hickory are synonyms defined as:

pignut hickory and black hickory: an American hickory tree having bitter nuts

Other synonyms of pignut hickory include brown hickory, Carya glabra, pignut.

pignut hickory (noun)	black hickory (noun)
an American hickory tree having bitter nuts	an American hickory tree having bitter nuts
	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