There is a difference between a CNC lathe and a 4th axis rotary on a flat CNC. The former is more for turning with automated tool action which brings "yuge" repeatability and the latter is for ornamental carving. Ornamental carving can emulate turning in its simplest form, but it's not the same thing as turning with constant rotation. Rotaries (the second one) are not particularly well suited to actual "spinny" work like a CNC lathe is. What's kewel about a 4th axis setup is the ability to transfer/wrap complex 3D designs "around" the project workpiece. Different animal...