This difference was once more clear in Old English, 1. '(a)wacan' = (a)wake (to be awake, to arise, to come to be), and '(a)wæcnian = to be awake; 2. '(a)wæccan' = (a)watch (to wake up, rouse, stir), but now it seems they are merged for both transitive and intransitive meanings but dependent on context, and it seems that 'to. awaken' was intransitive (to be awake) rather than transitive (to cause to be awake).
So 'vågne' = awaken (transitive) and 'vække' = awake (intransitive).