litchi tree vs fruit tree

litchi tree and fruit tree both are nouns.

Word	Noun	Adjective	Verb	Adverb
litchi tree	Yes	No	No	No
fruit tree	Yes	No	No	No

As nouns, fruit tree is a hypernym of litchi tree; that is, fruit tree is a word with a broader meaning than litchi tree:

litchi tree: Chinese tree cultivated especially in Philippines and India for its edible fruit; sometimes placed in genus Nephelium
fruit tree: tree bearing edible fruit

litchi tree (noun)	fruit tree (noun)
Chinese tree cultivated especially in Philippines and India for its edible fruit; sometimes placed in genus Nephelium	tree bearing edible fruit