big shellbark vs hickory

big shellbark and hickory both are nouns.

Word	Noun	Adjective	Verb	Adverb
big shellbark	Yes	No	No	No
hickory	Yes	No	No	No

As nouns, hickory is a hypernym of big shellbark; that is, hickory is a word with a broader meaning than big shellbark:

big shellbark: hickory of the eastern United States resembling the shagbark but having a much larger nut
hickory: American hardwood tree bearing edible nuts

Other hypernyms of big shellbark include hickory tree.

big shellbark (noun)	hickory (noun)
hickory of the eastern United States resembling the shagbark but having a much larger nut	American hardwood tree bearing edible nuts
	valuable tough heavy hardwood from various hickory trees