Spline Points
Dragging spline points enables you to make quick adjustments to the shape of the spline, but you sacrifice precision.
Control Polygons
Dragging control polygons affords precision and speed, but spline point data does not update, and you cannot select between symmetrical or asymmetrical weighting control.
Spline Handles
Dragging different spline handles provides the greatest precision and feedback through the data displayed in the Spline PropertyManager under Parameters. This requires more time than the two other methods.