Interesting links:
R6850:
https://fccid.io/NCC/CCAI18LP1420T8 gives a different FCCID
https://fcc.report/FCC-ID/PY317300390 gives PY317300390
https://openwrt.org/toh/hwdata/netgear/netgear_r6850
R6350:
http://en.techinfodepot.shoutwiki.com/wiki/Netgear_R6350
https://openwrt.org/toh/netgear/r6350
There doesn't seem to be any difference. I physically have both of them in my hands. The boxes, antenna situation looks identical. I could not tell these apart, except for the stickers on the back, one saying R6350 one showing R6850, and of course showing different MAC addresses etc as usual.
I propose merging the two pages about the routers. The hardware is identical. I haven't actually flashed 23.05x Release on the R6850 but that's my next step.