red osier vs genus Salix

red osier and genus Salix both are nouns.

Word	Noun	Adjective	Verb	Adverb
red osier	Yes	No	No	No
genus Salix	Yes	No	No	No

red osier (noun)	genus Salix (noun)
Eurasian osier having reddish or purple twigs and bark rich in tannin	a large and widespread genus varying in size from small shrubs to large trees: willows
common North American shrub with reddish purple twigs and white flowers