Bithynia vs geographical region

Bithynia and geographical region both are nouns.

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

Bithynia (noun)	geographical 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