On the A320 and I have to believe the 737 for regulatory reaons
EGPWS is just GPWS with a terrain database isn't it. It compares GPS position and altitude against what the terrain database says.
Reactive Windshear warning uses aircraft sensors to trigger the alert when the aircraft is in a windshear.
Predictive windshear is based upon Weather Radar system detecting shifts in microwave pulses from the aircraft.