Carya illinoinsis vs pecan tree

Carya illinoinsis and pecan tree both are nouns.

Word	Noun	Adjective	Verb	Adverb
Carya illinoinsis	Yes	No	No	No
pecan tree	Yes	No	No	No

As nouns, Carya illinoinsis and pecan tree are synonyms defined as:

Carya illinoinsis and pecan tree: tree of southern United States and Mexico cultivated for its nuts

Other synonyms of Carya illinoinsis include Carya illinoensis, pecan.

Carya illinoinsis (noun)	pecan tree (noun)
tree of southern United States and Mexico cultivated for its nuts	tree of southern United States and Mexico cultivated for its nuts