Ball screws and ball splines are generally required to move an object horizontally or vertically whilst achieving a high positional accuracy and a rigid slop free movement.
A Ball Screw is a high-efficiency feed screw with balls making a rolling motion between the screw axis and the nut. Compared with a conventional moving nut on a thread, the ball screw reduces the power needed to drive an object up to 70%, making it most suitable for multiple installations where motor power is kept to a minimum.
A ball spline is a non-driven support bearing, keeping an object in line and allowing minimal movement in any direction other than that of travel. These are generally used in conjunction with a ball screw that provides the movement.