Yes, 3d printers run on Gcode, but there are many more parameters specified in printing than cnc. xyz movement of course, but also temperature, acceleration, line height/width, speed, part fan cooling, extruder fan cooling, limiting movements to within printed areas, the list goes on and on. All of that programming is done by the slicing software based on the settings you choose for the printer, for the filament, and for the model...though I think fusion can do it to an extent, but it can't keep up with features specific to newer printers
