poplar tree vs flowering tree

poplar tree and flowering tree both are nouns.

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

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

poplar tree: any of numerous trees of north temperate regions having light soft wood and flowers borne in catkins
flowering tree: any tree having seeds and ovules contained in the ovary

Other hypernyms of poplar tree include angiospermous tree.

poplar tree (noun)	flowering tree (noun)
any of numerous trees of north temperate regions having light soft wood and flowers borne in catkins	any tree having seeds and ovules contained in the ovary