Reality porn is porn that focuses more on a story than just pure sex. Contrary to the name, the women who are picked up by the filmer(s) are paid actresses who know what's going on before the guy shows up. However, while the whole event is a set-up, the outdoor portions are not filmed in closed off sets and the people in the background are real civilians.
Street Blowjobs, Bang Bus, and Milf Hunter are examples of popular reality porn sites. As fun as it is to believe their adventures are real, secretly filming a strange girl sucking your dick and posting the video on the internet, or picking a girl up in your van, doing her with the promise of money, and then dumping her off in the boonies and stealing her crutches would be very illegal.