pecan tree vs Carya illinoensis

pecan tree and Carya illinoensis both are nouns.

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

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

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

Other synonyms of pecan tree include Carya illinoinsis, pecan.

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