country vs res publica

country and res publica both are nouns.

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

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

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

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

country (noun)	res publica (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)