saltbush vs shrub

saltbush and shrub both are nouns.

Word	Noun	Adjective	Verb	Adverb
saltbush	Yes	No	No	No
shrub	Yes	No	No	No

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

saltbush: any of various shrubby plants of the genus Atriplex that thrive in dry alkaline soil
shrub: a low woody perennial plant usually having several major stems

Other hypernyms of saltbush include bush.

saltbush (noun)	shrub (noun)
any of various shrubby plants of the genus Atriplex that thrive in dry alkaline soil	a low woody perennial plant usually having several major stems