What kind of source do you expect me to give you? A study that interviews random people and asks them if they know the difference between civil and criminal law? I’d be very surprised if that has ever been done.
It’s merely my opinion that the difference between civil and criminal law is largely unclear to the average person. In defense of that I’d say my own anecdotal experience, the behavior of people during the recent ex-president’s trials, and the plethora of questions asking about it online. I think most people put “law” and “court” into one big bucket and don’t make too many sub divisions.
I’m not sure what else I could give as evidence here.