Camper or Topper?

In October, we bought a 1995 Nissan King-Cab pickup truck. What a blessing that little truck is! We were able to buy it because of some generous gifts by some very special people. Our truck is 4-wheel-drive with a manual transmission. We have had to do some major maintenance work on it (including the new radiator we had to install this week); however, it is running good now. The one thing that Jose Luis wanted to get for it was a camper (as they say in Spanish). There has been some confusion over exactly what this is, so I am adding a photo of our truck with its campler: