Rockies vs Rocky Mountains

Rockies and Rocky Mountains both are nouns.

Word	Noun	Adjective	Verb	Adverb
Rockies	Yes	No	No	No
Rocky Mountains	Yes	No	No	No

As nouns, Rockies and Rocky Mountains are synonyms defined as:

Rockies and Rocky Mountains: the chief mountain range of western North America; extends from British Columbia to northern New Mexico; forms the continental divide

Rockies (noun)	Rocky Mountains (noun)
the chief mountain range of western North America; extends from British Columbia to northern New Mexico; forms the continental divide	the chief mountain range of western North America; extends from British Columbia to northern New Mexico; forms the continental divide