3D printing leaves a soft texture on every print and each of the finishing options offers a benefit over a raw 3D print. Processed and Premium options will have the part tumbled in a media tumbler to remove bits of texture and rough spots on the part, with the only difference being the length of time they are in the machine. Processed is best described as the texture of an egg shell while Premium plastic still has a slight texture, but it should be slightly smoother, meaning skin will glide across it a little easier. The Smooth finish is a chemical vapor process that chemically "melts" the outer surface of the part and leaves an extremely smooth finish that's also water-tight and highly glossy. MJF PA12 parts are printed at a finer layer height, and offers a finish that is fairly smooth without any post-processing. Shapeways goes into detail on those questions here