The two primary differences are the HPGMT10 supports both 24V and -48V operation, where the 20HPGMT05BNR only supports -48V operation. The second difference is the 20HPGMT05BNR includes circuitry for noise filtering on the power lines, which helps protect sensitive equipment. However, unless your application requires the noise filtering capabilities Telect recommends the HPGMT10 panel.