It makes sense comparing Yamaha RX-V485 vs Onkyo TX-RZ630 because they both are able to give some premium features.
A significant difference between the receivers in the number of channels, Yamaha RX-V485 has 5.1 versus 9.2 for Onkyo TX-RZ630. Regarding power, then RX-V485 has such a W/Ohm ratio - 80/8, 145/6 when TX-RZ630 has a power of 90/8, 215/6. The THD is 0.09% for the RX-V485 but 0.08% for the TX-RZ630.
Characteristics of digital to analog converter (DAC) are different, Burr-Brown 384 KHz/32-bit for RX-V485 and AK4458 384 KHz/32-bit for the TX-RZ630. Both the RX-V485 and the TX-RZ630 support Bi-amping. Each of the AV receivers can transmit an audio signal directly to the amplifier and bypasses any DSP processing. Rivals from our review have Bluetooth support. The Yamaha RX-V485 has support for AirPlay, AirPlay 2, and its competitor in our comparison - AirPlay. Spotify can be used on each receiver. The RX-V485 can work with the audio stream from Deezer, TIDAL, Pandora, Napster, SiriusXM, and the TX-RZ630 can receive a content from Deezer, TIDAL, Pandora.
Both AV receivers support HDR10 technology (High dynamic range). Compared AV receivers retain the quality of 4K/60Hz signal when transmitting from a source to a TV or projector. HDMI signal transmission in standby mode is implemented in each of the devices. The RX-V485 can scale the input HDMI signal, unlike the TX-RZ630. The HDR standard - Dolby Vision is supported by these receivers.
The Yamaha RX-V485 has 4/1 HDMI inputs/outputs versus 7/2 HDMI connectors of the Onkyo TX-RZ630. The HDMI Audio Return Channel (ARC) feature supports both devices. The HDMI eARC is available only on the RX-V485. The Consumer Electronics Control (CEC) feature is present in most modern AV receivers and the models in our comparison are no exception. The RX-V485 supports the protection of digital content of the standard HDCP 2.3, versus HDCP 2.2 in the TX-RZ630. The TX-RZ630 has a built-in phono stage for connecting a vinyl player.
The RX-V485 supports 2 Multi-room zones, versus 3 for the TX-RZ630. The RX-V485 supports voice control via Amazon Alexa, Google Assistant, Siri, and the TX-RZ630 - Google Assistant. An ECO mode is only available for the RX-V485. Both RX-V485 and TX-RZ630 can be configured using the Setup assistant.
Only the TX-RZ630 has a Dolby Atmos multichannel audio format support. A surround technology DTS:X is supported only by the TX-RZ630.