Can the Xbox One really run Windows 8 apps?

Can the Xbox one really run Windows 8 apps? I mean it has a Windows Kernel, Windows supports really big resolutions, so whats really stopping Microsoft? I mean talk about their 'One Experience in all their devices' vision this would be a first big step and would make their unity across their platforms even better than google or apples.

Side-question; Is it just me, or is the Xbox One UI better than PS4?. The PS4 UI looks clunky and terrible. Windows 7 UI implemented somewhere it does not belong. And Microsoft this is where Metro UI are supposed to be, consoles not Windows..