Either one will allow you to machine parts. Turning is a two axis process and the two way gives both the “X” and “Z”. To this day I do not know what the advantage of the third cross slide is. It is set at 90 degrees to the “X” slide. The three way slides cost more money and are harder to find but I personally see no advantage to them. Perhaps somone out there knows what a three way slide can do that a two way slide can not do. As a rule of thumb, the more movements that are added to a machine, the less stable the machine is. I have had no problems with either configuration. I guess it is possible that the three way was a marketing ploy thought up by the WOLF JAHN sales department. I do not know.