guava bush vs fruit tree

guava bush and fruit tree both are nouns.

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

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

guava bush: small tropical American shrubby tree; widely cultivated in warm regions for its sweet globular yellow fruit
fruit tree: tree bearing edible fruit

guava bush (noun)	fruit tree (noun)
small tropical American shrubby tree; widely cultivated in warm regions for its sweet globular yellow fruit	tree bearing edible fruit