Caucasian vs Caucasus

Caucasian and Caucasus both are nouns.

Word	Noun	Adjective	Verb	Adverb
Caucasian	Yes	Yes	No	No
Caucasus	Yes	No	No	No

Caucasian (noun)	Caucasus (noun)
a number of languages spoken in the Caucasus that are unrelated to languages spoken elsewhere	a large region between the Black and Caspian seas that contains the Caucasus Mountains; oil is its major resource
a person of European descent with a light-skinned or pale complexion	the mountain range in Caucasia between the Black Sea and the Caspian Sea that forms part of the traditional border between Europe and Asia

Caucasian (adjective)	Caucasus (adjective)
of or relating to the geographical region of Caucasia
of or relating to Caucasian people