vox populi vs popular opinion

vox populi and popular opinion both are nouns.

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

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

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

Other synonyms of vox populi include opinion, public opinion.

vox populi (noun)	popular opinion (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