brown hickory vs pignut hickory

brown hickory and pignut hickory both are nouns.

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

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

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

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

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