lemon tree vs lemon

lemon tree and lemon both are nouns.

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

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

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

Other synonyms of lemon tree include Citrus limon.

lemon tree (noun)	lemon (noun)
a small evergreen tree that originated in Asia but is widely cultivated for its fruit	an artifact (especially an automobile) that is defective or unsatisfactory
	a strong yellow color
	a distinctive tart flavor characteristic of lemons
	yellow oval fruit with juicy acidic flesh
	a small evergreen tree that originated in Asia but is widely cultivated for its fruit