Some Form commands let you manage either control points or surface points.
A T-Spline body is driven by a control frame. The control frame is displayed in box display and control frame display.
Control points are the vertices on the control frame. Control points can be managed using command such as Edit Form and Pull.
Surface points are vertices displayed on the T-Spline surface. When editing a T-Spline body, you are changing the control frame even when in smooth display mode. The surface points exist to provide an object to select when editing in smooth display mode.