genus Salix vs Salix pyrifolia

genus Salix and Salix pyrifolia both are nouns.

Word	Noun	Adjective	Verb	Adverb
genus Salix	Yes	No	No	No
Salix pyrifolia	Yes	No	No	No

genus Salix (noun)	Salix pyrifolia (noun)
a large and widespread genus varying in size from small shrubs to large trees: willows	small shrubby tree of eastern North America having leaves exuding an odor of balsam when crushed