How does one diferentiate between a hobbyist's sophisticated radio controlled model and a drone/UAV requiring CASA or FAA approval/licensing?
The differentiation applies when you fly a model aircraft for reward. In Oz you can fly a R/C model up to 150kg now, so long as it has approval from the controlling body, in that case the MAAA. It must stay within the pilots line of sight.
Now if you take a 1kg model and attach a camera and fly it either line of sight or using downlink video, and you sell film or photos from that flight, you are doing it commercially and must be licensed to do so by CAsA.