water bitternut vs hickory tree

water bitternut and hickory tree both are nouns.

Word	Noun	Adjective	Verb	Adverb
water bitternut	Yes	No	No	No
hickory tree	Yes	No	No	No

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

water bitternut: hickory of southern United States having many narrow leaflets and rather bitter nuts
hickory tree: American hardwood tree bearing edible nuts

Other hypernyms of water bitternut include hickory.

water bitternut (noun)	hickory tree (noun)
hickory of southern United States having many narrow leaflets and rather bitter nuts	American hardwood tree bearing edible nuts