While both consoles have 8gb of RAM (albeit, the PS4 having DDR5 compared to the XBO having DDR3), 3gb of the XBO RAM is reserved for system use (3 operating systems and all that).
Whereas the system RAM for the PS4 is apparently completely separate, meaning games could have access to all 8gb.

The thing is, the difference in stats probably doesn't mean all that much.

As far as multi-format games go, the limiting factor will probably be the lowest common denominator.

It will probably only be exclusive first/second party games that will really highlight any superior capabilities of either machine.

I'm really not interested in a console war or X v Y as an arguement, but I have to be honest.
A deficit of 3gb of RAM, and using a slower clock speed to boot, seems like quite a significant shortfall.

Of course, the Wii U only has 2gb RAM, though that's still 4x the amount of the Xbox 360 and we always knew that the Wii U was not setting out to be the ultimate hardware powerhouse.
Like the Wii, it's not a direct power competitor to the other two, it's just a good percentage better than either the Xbox 360 or PS3 and will finally let Nintendo do some very new and different things given that they had basically been using the same hardware (Gamecube) for 11 years.