grouseberry vs blueberry bush

grouseberry and blueberry bush both are nouns.

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

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

grouseberry: shrub of northwestern North America bearing red berries
blueberry bush: any of numerous shrubs of the genus Vaccinium bearing blueberries

Other hypernyms of grouseberry include blueberry.

grouseberry (noun)	blueberry bush (noun)
shrub of northwestern North America bearing red berries	any of numerous shrubs of the genus Vaccinium bearing blueberries