currant bush vs shrub

currant bush and shrub both are nouns.

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

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

currant bush: any of various deciduous shrubs of the genus Ribes bearing currants
shrub: a low woody perennial plant usually having several major stems

Other hypernyms of currant bush include bush.

currant bush (noun)	shrub (noun)
any of various deciduous shrubs of the genus Ribes bearing currants	a low woody perennial plant usually having several major stems