It's mostly under the scenes changes. And the Xbox One graphics card is a DirectX 12 card, but we don't know yet how much it will effect gaming.
It will be running Windows 10, and it will open Windows 10 Universal apps for the Xbox One. Developers will be able to design something for Windows 10, Xbox One, and Windows 10 Phone all at the same time.
TL/DR: Should run better, fast, with more options.







