bighorn sheep vs Rocky Mountain bighorn

bighorn sheep and Rocky Mountain bighorn both are nouns.

Word	Noun	Adjective	Verb	Adverb
bighorn sheep	Yes	No	No	No
Rocky Mountain bighorn	Yes	No	No	No

As nouns, bighorn sheep and Rocky Mountain bighorn are synonyms defined as:

bighorn sheep and Rocky Mountain bighorn: wild sheep of mountainous regions of western North America having massive curled horns

Other synonyms of bighorn sheep include bighorn, cimarron, Ovis canadensis, Rocky Mountain sheep.

bighorn sheep (noun)	Rocky Mountain bighorn (noun)
wild sheep of mountainous regions of western North America having massive curled horns	wild sheep of mountainous regions of western North America having massive curled horns