melon tree vs fruit tree

melon tree and fruit tree both are nouns.

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

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

melon tree: tropical American shrub or small tree having huge deeply palmately cleft leaves and large oblong yellow fruit
fruit tree: tree bearing edible fruit

melon tree (noun)	fruit tree (noun)
tropical American shrub or small tree having huge deeply palmately cleft leaves and large oblong yellow fruit	tree bearing edible fruit