quince bush vs fruit tree

quince bush and fruit tree both are nouns.

Word	Noun	Adjective	Verb	Adverb
quince bush	Yes	No	No	No
fruit tree	Yes	No	No	No

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

quince bush: small Asian tree with pinkish flowers and pear-shaped fruit; widely cultivated
fruit tree: tree bearing edible fruit

quince bush (noun)	fruit tree (noun)
small Asian tree with pinkish flowers and pear-shaped fruit; widely cultivated	tree bearing edible fruit