fringe bush vs fringe tree

fringe bush and fringe tree both are nouns.

Word	Noun	Adjective	Verb	Adverb
fringe bush	Yes	No	No	No
fringe tree	Yes	No	No	No

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

fringe bush: small bushy tree of southeastern United States having profuse clusters of white flowers
fringe tree: any of various small decorative flowering trees or shrubs of the genus Chionanthus

fringe bush (noun)	fringe tree (noun)
small bushy tree of southeastern United States having profuse clusters of white flowers	any of various small decorative flowering trees or shrubs of the genus Chionanthus