Hi Stephen, not exactly. R730 was built before Wi-Fi Alliance adopted Wi-Fi 6 certification. So, even though this AP is compliant with a subset of 802.11ax, it's never going to be Wi-Fi 6 certified (as opposed to R850).
A specific difference I'm aware of is uplink+downlink OFDMA support in R850 versus downlink only in R730
FCC has a Declaration of Similarity document. The R850 and R730 are basically identical EXCEPT the R850 has the Hawkeye v2 chipset (IPQ8078v2) which supports UL+DL-OFDMA and is Wifi 6 certifiable.
The R730 has the original v1 Hawkeye which definitely does not support UL-OFDMA. Whether or not it properly supports DL-OFDMA is still up in the air, with some vendors supporting it and others not (Ruckus as of the latest SmartZone release does not support OFDMA in either direction on R730)