hickory tree vs hickory

hickory tree and hickory both are nouns.

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

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

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