Caucasus vs Transcaucasia

Caucasus and Transcaucasia both are nouns.

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

Caucasus (noun)	Transcaucasia (noun)
a large region between the Black and Caspian seas that contains the Caucasus Mountains; oil is its major resource	a geographical region to the south of the Caucasus Mountains and to the north of Turkey that comprises Georgia and Armenia and Azerbaijan
the mountain range in Caucasia between the Black Sea and the Caspian Sea that forms part of the traditional border between Europe and Asia