The different holes on the sway bar will determine the stiffness of the bar. The hole closer to the bar will be stiffer and the hole further away will be softer.
It does not necessarily mean less or more "over steering", but it will affect the spring balance front to rear. And depending on the rest of the setup, it could cause the vehicle to be more oversteer biased even on the softer setting.
Edit: Let me just explain a little more on why this works, so everyone will remember later. Holes closer to the bar have shorter moment arm. The force is applied at the hole and creates a moment or a twisting about the axis of the bar. If the hole is closer, the moment arm is shorter and the moment will be smaller. This means it takes more force to from the wheel to twist the bar, effectively making the bar stiffer relative to everything. The rate of the bar will never change, just the amount of force needed to twist it. So a hole further away from the bar, would have a longer moment arm and would need less force to twist the bar a certain amount. It's the same principle as using a breaker bar to generate more torque when loosening a bolt.
Tim
