I think this will be difficult to explain, but I'll give it a shot anyway
For importing; yes, 3D is basically the same. Import the 3D file to CAM and it will ouput the GCODE. But going 3D; the CAM process is a bit more complicated. You need to decide how to machine the different features on the part using a number of tool path options. Some CAM software have lots and lots of options..
I hope that was of some help.. If you need more info just ask