Salix pyrifolia vs willow tree

Salix pyrifolia and willow tree both are nouns.

Word	Noun	Adjective	Verb	Adverb
Salix pyrifolia	Yes	No	No	No
willow tree	Yes	No	No	No

As nouns, willow tree is a hypernym of Salix pyrifolia; that is, willow tree is a word with a broader meaning than Salix pyrifolia:

Salix pyrifolia: small shrubby tree of eastern North America having leaves exuding an odor of balsam when crushed
willow tree: any of numerous deciduous trees and shrubs of the genus Salix

Other hypernyms of Salix pyrifolia include willow.

Salix pyrifolia (noun)	willow tree (noun)
small shrubby tree of eastern North America having leaves exuding an odor of balsam when crushed	any of numerous deciduous trees and shrubs of the genus Salix