1. Input lag aka 'reaction from the time I press the button to response on tv'.
2. Pixel response time aka blur/ghosting.
Try playing some fast games like DMC or Gears, firts on normal or whatever mode your using and then switch to game mode, its like day and night, how can u not tell the difference..? Like i've said, I did some measurments with my laptop, the difference was approx 90ms in normal modes and 20 in game/m. And in that one it blurs to much, when you look around I see that immediatly, had a good plasma for 5 years.