SEEED motor shield and servos- Just need clarification

Hey friends,
So I have built a OAR and now I want to add a servo to improve the function, and on my motorshield, it has two output pins for a "stepper" motor. I have looked into this but I have gotten tons of different info, and I now can't tell what the difference is between a servo and a stepper, and whether I can drive a servo on my shield, and whether I'll need external power. If anyone can clarify this whole shiz-kam-bang for me I'd be greatly appreciative, and even more so if they could point me in the direction of a instruction link for servos with motor shields.

stepper motor is a 4 wire electric motor in which the coil pairs are energized in sequence to make the motor move in discrete steps, you can count the steps of the motor to precisely control location or distance moved

a servo moves a designated distance based on the width of a pwm signal sent to and interpreted by an onboard controler, or something like that

OK, so can I use a servo on my board?