swamp hickory vs hickory

swamp hickory and hickory both are nouns.

Word	Noun	Adjective	Verb	Adverb
swamp hickory	Yes	No	No	No
hickory	Yes	No	No	No

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

swamp hickory: hickory of the eastern United States having a leaves with 7 or 9 leaflets and thin-shelled very bitter nuts
hickory: American hardwood tree bearing edible nuts

Other hypernyms of swamp hickory include hickory tree.

swamp hickory (noun)	hickory (noun)
hickory of the eastern United States having a leaves with 7 or 9 leaflets and thin-shelled very bitter nuts	American hardwood tree bearing edible nuts
	valuable tough heavy hardwood from various hickory trees