There's at least one more type of camper. It's usually a "Starter" unit -- a graduation up from a traditional tent. Think of it as a tent on wheels with a few mod-cons. In fact some pop-ups have roof-mounted A/C and satellite dishes! Most have indoor kitchens and room for a portapotty
Here are 2 examples. The first picture is a typical pop-up camper. The second has 3 slide out trays meaning it can sleep 6 people who are really good friends.