dwarf gray willow vs genus Salix

dwarf gray willow and genus Salix both are nouns.

Word	Noun	Adjective	Verb	Adverb
dwarf gray willow	Yes	No	No	No
genus Salix	Yes	No	No	No

dwarf gray willow (noun)	genus Salix (noun)
willow shrub of dry places in the eastern United States having long narrow leaves canescent beneath	a large and widespread genus varying in size from small shrubs to large trees: willows