Belarus vs Belorussia

Belarus and Belorussia both are nouns.

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

As nouns, Belarus and Belorussia are synonyms defined as:

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

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

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