While 3D printing turns a filament or resin into an object by printing each layer, a CNC mill (or CNC router) carves a shape out of a slab of material.Both methods of manufacturing use 3D models, and have computers input the directions to print the 3D model to the device itself.  CNC stands for computer numerical control, and this type of machine is related to the manual tools used in woodworking. Source: Wikipedia.Where a 3D printer either uses a laser or a heated filament, CNC routers use cutting tools to carve precise shapes.