buckeye vs flowering tree

buckeye and flowering tree both are nouns.

Word	Noun	Adjective	Verb	Adverb
buckeye	Yes	No	No	No
flowering tree	Yes	No	No	No

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

buckeye: tree having palmate leaves and large clusters of white to red flowers followed by brown shiny inedible seeds
flowering tree: any tree having seeds and ovules contained in the ovary

Other hypernyms of buckeye include angiospermous tree.

buckeye (noun)	flowering tree (noun)
tree having palmate leaves and large clusters of white to red flowers followed by brown shiny inedible seeds	any tree having seeds and ovules contained in the ovary
the inedible nutlike seed of the horse chestnut