Right; the Delta (aka hexapod or parallel kinematics) machines use a different design principle; instead of Cartesian movements (in X Y and Z planes) they suspend the extruder from arms that get longer or shorter and hinge. That has the potential of moving the hot end more quickly, with less expense devoted to sliding parts. The mathematics involved in computing their motions are more complex, but computers are good at that.

Andrew Werby
www.computersculpture.com