region vs Principality of Achaea

region and Principality of Achaea both are nouns.

Word	Noun	Adjective	Verb	Adverb
region	Yes	No	No	No
Principality of Achaea	Yes	No	No	No

region (noun)	Principality of Achaea (noun)
a part of an animal that has a special function or is supplied by a given artery or nerve	a region of ancient Greece on the north coast of the Peloponnese
a knowledge domain that you are interested in or are communicating about
the extended spatial location of something
a large indefinite location on the surface of the Earth
the approximate amount of something (usually used prepositionally as in `in the region of')