EPIRBs that'll locate you to within 10cm
2 types of Beacons (EPIRB PLB ELT etc)
No GPS - ~5 nm and up to 3 hrs to get that depending on what the satellites are doing
GPS 400 ft in a few minutes. The beacon may have a better position from it's gps but the code string limits what it can send.
Some people want to save the extra $150 a GPS beacon costs.