Prunus pumila vs shrub

Prunus pumila and shrub both are nouns.

Word	Noun	Adjective	Verb	Adverb
Prunus pumila	Yes	No	No	No
shrub	Yes	No	No	No

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

Prunus pumila: small straggling American cherry growing on sandy soil and having minute scarcely edible purplish-black fruit
shrub: a low woody perennial plant usually having several major stems

Other hypernyms of Prunus pumila include bush.

Prunus pumila (noun)	shrub (noun)
small straggling American cherry growing on sandy soil and having minute scarcely edible purplish-black fruit	a low woody perennial plant usually having several major stems