mountain sumac vs black sumac

mountain sumac and black sumac both are nouns.

Word	Noun	Adjective	Verb	Adverb
mountain sumac	Yes	No	No	No
black sumac	Yes	No	No	No

As nouns, mountain sumac and black sumac are synonyms defined as:

mountain sumac and black sumac: common nonpoisonous shrub of eastern North America with compound leaves and green paniculate flowers followed by red berries

Other synonyms of mountain sumac include dwarf sumac, Rhus copallina, shining sumac.

mountain sumac (noun)	black sumac (noun)
common nonpoisonous shrub of eastern North America with compound leaves and green paniculate flowers followed by red berries	common nonpoisonous shrub of eastern North America with compound leaves and green paniculate flowers followed by red berries