The simple answer is the APR Control unloads the compressor and hot gas bypass loads the evaporator. THE APR CONTROL IS COMPATIBLE WITH MICRO-CHANNEL CONDENSOR COILS WHILE STANDARD HOT GAS BYPASS TO THE DISTRIBUTOR OF THE EVAPORATOR COIL, IS NOT AN ACCEPTABLE OPTION FOR MICRO CHANNEL COILS. THE APR CONTROL IS ACCEPTED BY ASHRAE 90.1 STANDARDS AND HOT GAS BYPASS IS NOT.