An exterior discharge line is a drain installed leading to the low point of the property, sending water away from the home. Since the system is inside, there's no dirt to clog it up and water is discharged effectively via the sump pump.
IceGuard is a simple addition to your already existing sump pump. It allows water to escape when the discharge line is frozen and prevents your basement flooding in cold weather. IceGuard is completely automatic, meaning after the initial installation, it's done.