I know for the PS4 - the system "explicitly" tells you to properly shut-down the console by choosing the "Turn Off PS4" option if you plan to disconnect the power supply of the console - instead of the "Standby". I figure if you get a power-outage while the system was busy background downloading something in "Standby Mode" - it could potentially corrupt the HDD in the console. In fact - I believe the PS4 will actually warn you if you accidentally unplugged the system during it's "Standby Mode" - and will automatically check the HDD/filesystem for corruption after it starts up again.
However, Microsoft doesn't seem to give any of these explicit warning on the XBOX ONE for it's Instant-On vs Energy Saver power modes. There is only one way to "Turn Off" the XBOX one - and that by going to menu and asking XBOX to "turn-off". But what about things like power-outages? What if during Instant-On - you had a power-outage - could that be worse than say for it to be on Energy Saver?
Or has Microsoft designed it to that as long as you "Turn Off" the XBOX (with whatever Power Mode its in) - you can safely disconnect the power-supply anytime you want?