genus Salix vs Salix sitchensis

genus Salix and Salix sitchensis both are nouns.

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

genus Salix (noun)	Salix sitchensis (noun)
a large and widespread genus varying in size from small shrubs to large trees: willows	small shrubby tree of western North America (Alaska to Oregon)