Western Empire vs Roman Empire

Western Empire and Roman Empire both are nouns.

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

Western Empire (noun)	Roman Empire (noun)
the western part after the Roman Empire was divided in 395; it lasted only until 476	an empire established by Augustus in 27 BC and divided in AD 395 into the Western Roman Empire and the eastern or Byzantine Empire; at its peak lands in Europe and Africa and Asia were ruled by ancient Rome