Clean Cut
A Clean Cut is where the machine will cut all the way through the material and the cut parts will fall away from each other leaving only minimal dross on the bottom edge which can easily be pulled off using pliers etc.
The cutting marks will start off straight and then give a slope of a small angle towards the bottom of the cut. The metal should require no extra working before being welded together etc.
Severance Cut
A Severance Cut is where the user is using the machine close to its maximum cutting thickness capability. The cutting speed will be much slower compared to a clean cut and the metal will require some cleaning up towards the bottom edge.