Western Roman Empire vs Western Empire

Western Roman Empire and Western Empire both are nouns.

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

As nouns, Western Roman Empire and Western Empire are synonyms defined as:

Western Roman Empire and Western Empire: the western part after the Roman Empire was divided in 395; it lasted only until 476

Western Roman Empire (noun)	Western Empire (noun)
the western part after the Roman Empire was divided in 395; it lasted only until 476	the western part after the Roman Empire was divided in 395; it lasted only until 476