mountain blue berry vs bilberry

mountain blue berry and bilberry both are nouns.

Word	Noun	Adjective	Verb	Adverb
mountain blue berry	Yes	No	No	No
bilberry	Yes	No	No	No

As nouns, mountain blue berry and bilberry are synonyms defined as:

mountain blue berry and bilberry: erect blueberry of western United States having solitary flowers and somewhat sour berries

Other synonyms of mountain blue berry include thin-leaved bilberry, Viccinium membranaceum.

mountain blue berry (noun)	bilberry (noun)
erect blueberry of western United States having solitary flowers and somewhat sour berries	blue-black berries similar to American blueberries
	erect blueberry of western United States having solitary flowers and somewhat sour berries
	erect European blueberry having solitary flowers and blue-black berries