Byelorussia vs Republic of Belarus

Byelorussia and Republic of Belarus both are nouns.

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

As nouns, Byelorussia and Republic of Belarus are synonyms defined as:

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

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

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