res publica vs country

res publica and country both are nouns.

Word	Noun	Adjective	Verb	Adverb
res publica	Yes	No	No	No
country	Yes	No	No	No

As nouns, res publica and country are synonyms defined as:

res publica and country: a politically organized body of people under a single government

Other synonyms of res publica include body politic, commonwealth, land, nation, state.

res publica (noun)	country (noun)
a politically organized body of people under a single government	a politically organized body of people under a single government
	the people who live in a nation or country
	the territory occupied by a nation
	an area outside of cities and towns
	a particular geographical region of indefinite boundary (usually serving some special purpose or distinguished by its people or culture or geography)