Salix herbacea vs willow

Salix herbacea and willow both are nouns.

Word	Noun	Adjective	Verb	Adverb
Salix herbacea	Yes	No	No	No
willow	Yes	No	No	No

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

Salix herbacea: widely distributed boreal shrubby willow with partially underground creeping stems and bright green glossy leaves
willow: any of numerous deciduous trees and shrubs of the genus Salix

Other hypernyms of Salix herbacea include willow tree.

Salix herbacea (noun)	willow (noun)
widely distributed boreal shrubby willow with partially underground creeping stems and bright green glossy leaves	a textile machine having a system of revolving spikes for opening and cleaning raw textile fibers
	any of numerous deciduous trees and shrubs of the genus Salix