grouseberry vs grouse whortleberry

grouseberry and grouse whortleberry both are nouns.

Word	Noun	Adjective	Verb	Adverb
grouseberry	Yes	No	No	No
grouse whortleberry	Yes	No	No	No

As nouns, grouseberry and grouse whortleberry are synonyms defined as:

grouseberry and grouse whortleberry: shrub of northwestern North America bearing red berries

Other synonyms of grouseberry include grouse-berry, Vaccinium scoparium.

grouseberry (noun)	grouse whortleberry (noun)
shrub of northwestern North America bearing red berries	shrub of northwestern North America bearing red berries