suzerain vs res publica

suzerain and res publica both are nouns.

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

As nouns, res publica is a hypernym of suzerain; that is, res publica is a word with a broader meaning than suzerain:

suzerain: a state exercising a degree of dominion over a dependent state especially in its foreign affairs
res publica: a politically organized body of people under a single government

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

suzerain (noun)	res publica (noun)
a state exercising a degree of dominion over a dependent state especially in its foreign affairs	a politically organized body of people under a single government