One is an m570 the other an ms trackball optical. Now obviously the newer m570 is going to be somewhat smoother because its newer. I've been using it for a bit and love it but I ordered a used ms trackball optical because I love the way it looked and it is the best feeling input device I've ever used. The only thing is the ball feels rough to use, that makes it harder to use. Almost like its rubbing against something, kinda sounds like it too and small movements kinda stick on it. Does that mean it needs to be lubbed, if so what do I use? Are the barrings just bad, if so can I replace those? Or even a new ball? I tried cleaning it and it did help some. One of these is going to work with me so if I can't fix the trackball optical I'll just take that with me, but I was kinda hoping to keep it at home since it looks so much nicer.