Experiment with Exposure Simulator

When i took the picture on manual with the ISO at 400, Aperture at F8 and shutter speed at 1/80 sec. the picture was nice and bright but the little girls windmill was blurred. But when i kept everything the same except shutter speed to 1/400sec on using shutter priority the picture was darker with no blur. Then i tried the exact same thing on Aperture priority and the picture came out bright with no blur