popular opinion vs vox populi

popular opinion and vox populi both are nouns.

Word	Noun	Adjective	Verb	Adverb
popular opinion	Yes	No	No	No
vox populi	Yes	No	No	No

As nouns, popular opinion and vox populi are synonyms defined as:

popular opinion and vox populi: a belief or sentiment shared by most people; the voice of the people

Other synonyms of popular opinion include opinion, public opinion.

popular opinion (noun)	vox populi (noun)
a belief or sentiment shared by most people; the voice of the people	a belief or sentiment shared by most people; the voice of the people