I am glad you raised this question Tim. Let me explain the difference through this example. Imagine this scenario: You take your brand new sedan for a spin, but accidentally end up creating a dent at the back. Just a few seconds ago you were elated with your new possession, but after the incident, your entire cluster of thought seems to revolve around that very incident. You are involuntarily involved in replaying the whole sequence of event multiple times. Your mind seems to be hijacked completely by that incident. But mind you, this entire episode is taking place without you realizing it & may extend up to more than a couple of days. However, the moment you bring consciousness into play, the autopilot mode will cease to occupy the center stage. Hence the choice of indulging in responsive/involuntary thoughts is entirely yours.