There are multiple changes with the top board. The fan sounds quieter version compared to the V1. If you look closely at the bottom left, there are also an IR receiver and a 3 pins (new in V2).
Here is the close up of the IR receiver and the jumper configuration. I am running all my Pi 4s via POE and using Home Assistant to turn POE on/off the network ports connecting to my Raspberry Pi. If I short pins 2 and 3, I can finally power the Pi automatically every time POE is enabled.
The IR receiver will come in handy as it means I can ditch my USB IR receiver and use this instead. Or add remote control to Snakeoil somehow as a Squeezebox like player.
Wonder if a V3 will include IR blaster support? One can only hope.