It makes sense comparing Onkyo TX-RZ710 vs Onkyo TX-8020 because they both are able to give some premium features.
A significant difference between the receivers in the number of channels, Onkyo TX-RZ710 has 7.2 versus 2 for Onkyo TX-8020. Regarding power, then TX-RZ710 has such a W/Ohm ratio - 175/6 1KHz when TX-8020 has a power of 90/6 20Hz-20KHz. The THD is 0.08% for the TX-RZ710 but 0.03% for the TX-8020.
Characteristics of digital to analog converter (DAC) are different, AK4458 384 KHz/32-bit for TX-RZ710 and 192 KHz/24-bit for the TX-8020. Only the TX-RZ710 supports Bi-amping feature. Each of the AV receivers can transmit an audio signal directly to the amplifier and bypasses any DSP processing. Only the TX-RZ710 has Bluetooth support. The Apple Music service is implemented on considered devices: AirPlay. Only the TX-RZ710 supports Spotify.
Only the Onkyo TX-RZ710 has support for High dynamic range (HDR). Only the TX-RZ710 provides HDMI signal transmission in standby mode. The TX-RZ710 can scale the input HDMI signal, unlike the TX-8020. The HDR standard - Dolby Vision is not supported by these receivers. Only the TX-RZ710 supports HDMI Audio Return Channel (ARC). Unfortunately, HDMI eARC is not available on monitored devices. Of the two receivers in our comparison, HDMI CEC is present in only the TX-RZ710. These compared receivers have a built-in phono stage for connecting a vinyl player. A voice control is not available. An ECO mode is only available for the TX-RZ710. Unfortunately, the setup assistant is not available in each of the models.
Only the TX-RZ710 has a Dolby Atmos multichannel audio format support. A surround technology DTS:X is supported only by the TX-RZ710.
The Onkyo TX-RZ710 is better receiver in this comparison. Check Onkyo TX-RZ710 price