bighorn vs Rocky Mountain bighorn

bighorn and Rocky Mountain bighorn both are nouns.

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

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

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

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

bighorn (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