They're pretty close but IMO, Prologue has better graphics. The shadows in GT5 are really jaggy while prologue's is a lot smoother. The lighting is also better in Prologue and the game looks less dark than GT5. The cockpit view is about the same but there is a "Head Shake" effect that has been added in GT5 (As you can see in the video above) and the textures on the overall environment are a little higher in prologue.