blueberry bush vs shrub

blueberry bush and shrub both are nouns.

Word	Noun	Adjective	Verb	Adverb
blueberry bush	Yes	No	No	No
shrub	Yes	No	No	No

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

blueberry bush: any of numerous shrubs of the genus Vaccinium bearing blueberries
shrub: a low woody perennial plant usually having several major stems

Other hypernyms of blueberry bush include bush.

blueberry bush (noun)	shrub (noun)
any of numerous shrubs of the genus Vaccinium bearing blueberries	a low woody perennial plant usually having several major stems