Caucasia vs Caucasus

Caucasia and Caucasus both are nouns.

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

As nouns, Caucasia and Caucasus are synonyms defined as:

Caucasia and Caucasus: a large region between the Black and Caspian seas that contains the Caucasus Mountains; oil is its major resource

Caucasia (noun)	Caucasus (noun)
a large region between the Black and Caspian seas that contains the Caucasus Mountains; oil is its major resource	a large region between the Black and Caspian seas that contains the Caucasus Mountains; oil is its major resource
	the mountain range in Caucasia between the Black Sea and the Caspian Sea that forms part of the traditional border between Europe and Asia