Western Roman Empire vs geographic area

Western Roman Empire and geographic area both are nouns.

Word	Noun	Adjective	Verb	Adverb
Western Roman Empire	Yes	No	No	No
geographic area	Yes	No	No	No

Western Roman Empire (noun)	geographic area (noun)
the western part after the Roman Empire was divided in 395; it lasted only until 476	a demarcated area of the Earth