The RX-A2 (MSRP $800) is supposed to replace the RX-A880 (MSRP $900)
The RX-V6 (MSRP $600) is supposed to replace RX-V685 (MSRP $650)
Their specs look pretty much identical, except the A2 has 3YR warranty vs 2YR warranty of the V6.
Unless somebody opens them up and do a forensic comparison on all the parts, we probably won't know what the difference is.