Rotation speed and torque are the most important things to consider before buying power screwdrivers. Power screwdrivers are different than power drills even though they do same type of work. To drive nails one needs smaller speed than power drill, because we have to take care that bit does not slip or damage. Also some of the power drills also provide functionality like power screwdrivers; adjustable clutch gets slip when screw can no more tighten.
