white currant vs currant bush

white currant and currant bush both are nouns.

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

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

white currant: garden currant bearing small white berries
currant bush: any of various deciduous shrubs of the genus Ribes bearing currants

Other hypernyms of white currant include currant.

white currant (noun)	currant bush (noun)
the white translucent edible berry of a group of cultivars of the red currant (Ribes rubrum).	any of various deciduous shrubs of the genus Ribes bearing currants
garden currant bearing small white berries