black greasewood vs shrub

black greasewood and shrub both are nouns.

Word	Noun	Adjective	Verb	Adverb
black greasewood	Yes	No	No	No
shrub	Yes	No	No	No

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

black greasewood: low hardy much-branched spiny shrub common in alkaline soils of western America
shrub: a low woody perennial plant usually having several major stems

Other hypernyms of black greasewood include bush.

black greasewood (noun)	shrub (noun)
low hardy much-branched spiny shrub common in alkaline soils of western America	a low woody perennial plant usually having several major stems