In Fader space you have recorded fixed lighting states: channels whose levels change only with the master that controls them.
In the docks you can also assign dynamic content: channels whose intensity may change independent of the position of the master.
Those channels may be coming from these sources within White Cat:
But may also come from outside of White Cat:
Those channels are not in a fixed state. Their intensity may vary, so they are called dynamic content.
Assigning dynamic content to a dock simply provides a link to this content.