nation vs res publica

nation and res publica both are nouns.

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

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

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

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

nation (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
a federation of tribes (especially Native American tribes)