Belarus vs Byelorussia

Belarus and Byelorussia both are nouns.

Word	Noun	Adjective	Verb	Adverb
Belarus	Yes	No	No	No
Byelorussia	Yes	No	No	No

As nouns, Belarus and Byelorussia are synonyms defined as:

Belarus and Byelorussia: a landlocked republic in eastern Europe; formerly a European soviet

Other synonyms of Belarus include Belorussia, Byelarus, Republic of Belarus, White Russia.

Belarus (noun)	Byelorussia (noun)
a landlocked republic in eastern Europe; formerly a European soviet	a landlocked republic in eastern Europe; formerly a European soviet