samcheetah said:there are two types of position control; absolute positioning and relative positioning. the stepper motor uses relative positioning. you give the stepper a sequence of steps to move its rotor. at any time you know how many steps you are from some reference. the problem with such a system is establishing the reference and depending on the load the stepper might miss some steps so there might be a situation when you wont know where you actually are.
RC servos use absolute positioning. you always know where you are at any time. RC servos have lots of torque so there is no problem of missing steps as in steppers.
i hope that helps