I'm just repeating and adding to what petevette said.
Regular model cars you spray from the outside. Just like a real car. The R/C bodies are polycarbonate (lexan) and we spray from the inside. The clear body keeps the paint job looking better for a very long time. The paint for R/C cars is more flexable and in many cases water based.
The spray cans cany be used for R/C bodies. Be sure that you buy the paint for R/C bodies!! Pactora (sp) is the norm for R/C paint.