lemon tree vs Citrus limon

lemon tree and Citrus limon both are nouns.

Word	Noun	Adjective	Verb	Adverb
lemon tree	Yes	No	No	No
Citrus limon	Yes	No	No	No

As nouns, lemon tree and Citrus limon are synonyms defined as:

lemon tree and Citrus limon: a small evergreen tree that originated in Asia but is widely cultivated for its fruit

Other synonyms of lemon tree include lemon.

lemon tree (noun)	Citrus limon (noun)
a small evergreen tree that originated in Asia but is widely cultivated for its fruit	a small evergreen tree that originated in Asia but is widely cultivated for its fruit