The option angle from curve works similar to closest point option. The difference is that an additional fix tilt angle can be given to tilt the tool axis center line from the tilt curve to the direction of spindle main direction. This angle is the parameter fixed tilt angle. A value of 0 degrees here would make this option behave like closest point option.
The other differences that the direction of your tool axis is the projected length between your present toolpath point and the tilt curve. So it is the 2D distance.
The following example shows a wavy surface with a tilt curve above. You can see that the tool axis has the same direction like projected distance between surface and present toolpath point.
The view from the top shows the shortest 2D distance between tilt curve and toolpath point. The tool axis has always the same direction.
Setting a fixed angle the tool tilts in direction of the main axis. Usually the Z axis.