cranberry bush vs shrub

cranberry bush and shrub both are nouns.

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

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

cranberry bush: deciduous North American shrub or small tree having three-lobed leaves and red berries
shrub: a low woody perennial plant usually having several major stems

Other hypernyms of cranberry bush include bush.

cranberry bush (noun)	shrub (noun)
deciduous North American shrub or small tree having three-lobed leaves and red berries	a low woody perennial plant usually having several major stems