Generally a motion system is made up of a set (or stack) of linear and rotational stages.
A linear stage moves in a straight line, while a rotation stage moves in a partial or full circle.
A motion system generally is computer controlled and can perform fast, reliable, repeatable, and accurate positioning of loads.
Most systems will support motion in X and Y directions, which is referred to as an XY stack.
This allows for a motion controller to reliably and repeatably move to set positions with the linear stage.