@D Fosse Thank you very much for the answer! Basically in Windows' settings I chose "Show only on 2" (my external monitor) and then I checked "Make this my main display". Still, the problem's there. However, when I extend the monitors, the problem seems to disappear as colors are the same between ACR and Photoshop, but they look quite similar to those displayed by my laptop's monitor: duller and flatter. How do I know that in this case ACR is using the right profile?