pear vs fruit tree

pear and fruit tree both are nouns.

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

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

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

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