hickory vs hickory tree

hickory and hickory tree both are nouns.

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

As nouns, hickory and hickory tree are synonyms defined as:

hickory (noun)	hickory tree (noun)
American hardwood tree bearing edible nuts	American hardwood tree bearing edible nuts
valuable tough heavy hardwood from various hickory trees