Byelarus vs Belorussia

Byelarus and Belorussia both are nouns.

Word	Noun	Adjective	Verb	Adverb
Byelarus	Yes	No	No	No
Belorussia	Yes	No	No	No

As nouns, Byelarus and Belorussia are synonyms defined as:

Byelarus and Belorussia: a landlocked republic in eastern Europe; formerly a European soviet

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

Byelarus (noun)	Belorussia (noun)
a landlocked republic in eastern Europe; formerly a European soviet	a landlocked republic in eastern Europe; formerly a European soviet