Bithynia vs geographic region

Bithynia and geographic region both are nouns.

Word	Noun	Adjective	Verb	Adverb
Bithynia	Yes	No	No	No
geographic region	Yes	No	No	No

Bithynia (noun)	geographic region (noun)
an ancient country in northwestern Asia Minor in what is now Turkey; was absorbed into the Roman Empire by the end of the 1st century BC	a demarcated area of the Earth