Abib B , Aug 21, 2012; 03:53 a.m.
I do not have a 5n but on my cameras the difference is that tracking allows the focus point to move across the frame while AFC does not. AFC needs to be enabled for tracking to work: once you lock focus on the selected point the camera will track the object (far too slowly on my GX1).
You can test this very easily by panning the camera to simulate movement of a focus-locked object. The LCD will show that the focus point moves across the frame. This should also prove that AFC needs to be enabled for tracking to work. Conversely, moving the camera towards and away from the object will also show that the focus point stays fixed but that focus adjusts. This needs AFC but not object tracking.