When defining "public opinion", this would mean when you're asking to public of what they think personally. You are asking of their opinion of this specific matter. You want what they have to say, and why they would think this.
An example would be the following sentence:
Let's suppose that you would want to settle rights about slavery. You are debating whether you just continue this act, or to out it down. One thing that you could do personally is to ask the "public's opinion" about this matter, whether it would be "ok" to continue slavery, and why it would not.
This example right above would be an example of what the words "pubic opinion" would signify.
I hope this was found helpful, Have a great day!
