bitternut hickory vs bitter pignut

bitternut hickory and bitter pignut both are nouns.

Word	Noun	Adjective	Verb	Adverb
bitternut hickory	Yes	No	No	No
bitter pignut	Yes	No	No	No

As nouns, bitternut hickory and bitter pignut are synonyms defined as:

bitternut hickory and bitter pignut: hickory of the eastern United States having a leaves with 7 or 9 leaflets and thin-shelled very bitter nuts

Other synonyms of bitternut hickory include bitter hickory, bitternut, Carya cordiformis, swamp hickory.

bitternut hickory (noun)	bitter pignut (noun)
hickory of the eastern United States having a leaves with 7 or 9 leaflets and thin-shelled very bitter nuts	hickory of the eastern United States having a leaves with 7 or 9 leaflets and thin-shelled very bitter nuts