What do you call the cameras that you can take instant pictures from?

An SLR, or a single lens reflex camera. If you're thinking of "instant picture" as a physical production of the shot you just took, then a Polaroid camera is probably what you're referring to. I mean, the ones where a small photograph with a white border [and extra white space on the bottom of the frame] will pop out from a slit in the front of the camera seconds after you snap a shot. Unfortunately, since DSLRs (digital single lens reflex cameras) are becoming so popular, polaroids and other types of film cameras are not easy to find anymore.

I'm not quite sure if I answered your question, but hopefully this helps?!