The primary distinction between anterograde and retrograde amnesia lies in the timeline of memory loss relative to a specific causal event. Retrograde amnesia involves the loss of memories from the past, specifically those formed before the event. In contrast, anterograde amnesia is the inability to form new memories moving forward into the present, or after the event has occurred. This relationship can be visualized as a timeline with the event at the center, where retrograde amnesia extends backward into the past and anterograde amnesia extends forward into the present.