bitternut hickory vs bitter hickory

bitternut hickory and bitter hickory both are nouns.

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

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

bitternut hickory and bitter hickory: 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 pignut, bitternut, Carya cordiformis, swamp hickory.

bitternut hickory (noun)	bitter hickory (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