low-bush blueberry vs blueberry

low-bush blueberry and blueberry both are nouns.

Word	Noun	Adjective	Verb	Adverb
low-bush blueberry	Yes	No	No	No
blueberry	Yes	No	No	No

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

low-bush blueberry: low-growing deciduous shrub of northeastern North America having flowers in compact racemes and bearing sweet dark blue berries
blueberry: any of numerous shrubs of the genus Vaccinium bearing blueberries

Other hypernyms of low-bush blueberry include blueberry bush.

low-bush blueberry (noun)	blueberry (noun)
low-growing deciduous shrub of northeastern North America having flowers in compact racemes and bearing sweet dark blue berries	sweet edible dark-blue berries of either low-growing or high-growing blueberry plants
	any of numerous shrubs of the genus Vaccinium bearing blueberries