pear tree vs fruit tree

pear tree and fruit tree both are nouns.

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

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

pear tree: Old World tree having sweet gritty-textured juicy fruit; widely cultivated in many varieties
fruit tree: tree bearing edible fruit

pear tree (noun)	fruit tree (noun)
Old World tree having sweet gritty-textured juicy fruit; widely cultivated in many varieties	tree bearing edible fruit