You would have to look at the individual schools in question. I don't think one can generalize. Private schools are not necessarily able to protect children any more than a public school. They still learn about the world and are exposed to a variety of cultures and people.
My children did both at one time or another. I found the education they received at a private school far superior than the public school. There were smaller class sizes and the teachers seemed to really care about imparting a good education.
When we moved and they had to attend public school, we had to watch their education closely to be sure it was quality. Through the years in the public system they had both good and bad teachers - so we kept a close eye on their education.
What I loved about the private schools in our case is that both my children learned really good study habits that carried them through the rest of their school years.