They are all the 2021 newest Android TV box, and the name looks similar, but they are totally different.
- Chips: X96 X4 uses Amlogic S905X4 while X6 uses RockChip 3566
- RAM: X96 X6 support 8G while X96 X4 is only 4G
- Bluetooth: X96 X4 supports BT 4.1, but X96 X6 only supports BT 4.2
- LAN: X96 X6 supports 1000M, X96 X4 supports 100.
- Price: definitely different
Except for the above features, they all support 85 decodings and 2.5G/5G WiFi.