desert willow vs shrub

desert willow and shrub both are nouns.

Word	Noun	Adjective	Verb	Adverb
desert willow	Yes	No	No	No
shrub	Yes	No	No	No

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

desert willow: evergreen shrubby tree resembling a willow of dry regions of southwestern North America having showy purplish flowers and long seed pods
shrub: a low woody perennial plant usually having several major stems

Other hypernyms of desert willow include bush.

desert willow (noun)	shrub (noun)
evergreen shrubby tree resembling a willow of dry regions of southwestern North America having showy purplish flowers and long seed pods	a low woody perennial plant usually having several major stems