but you never move programs from 1 xb1 to another
Transmedia ramifications. This feature may not exists now but probably will in the future. Moving from your XB1 to the cloud so that you can play your games remotely in a more seamless fashion.
We have no ideal how the XB1 OS is actually configured but if its anything like Drawbridge then its not running three complete OSes.
Drawbridge is virtualization on the OS level not hardware level. Only the Host OS is sporting an OS kernel. The library OSes house the application services that make calls to a dynamic link library that is part of a kernel emulation layer that exists within the library OS. Calls are passed to and through the security layer to the kernel of Host OS below. Anything above the security layer runs in user mode while everything below runs in kernel mode.
When MS refactored Win7 for Drawbridge, the library OS of windows 7 was only 64 MB of binary requiring 16 MB of working memory, which is a lot lighter than the 512 mb of RAM and 4.8 GBs of disk space win7 requires when running as a guest OS on top of HyperV.
http://channel9.msdn.com/Shows/Going Deep/Drawbridge-An-Experimental-Library-Operating-System
The video goes into drawbridge's structure, how its different from vanilla windows/VMs and demos drawbridge running win7 and excel. They run excel locally then upload to cloud and access the spreadsheet remotely through IE.
That being said, the XB1 OS is structured differently than Drawbridge. Where as the user services in Drawbridge are part of the Host OS than runs above the security level, the XB1 has a third OS that house the user services and its Host OS doesn't seem to operate above the security layer/hypervisor.
Drawbridge was prototyped on the xbox 360 hardware at one point.
http://www.zdnet.com/article/microsoft-midori-mention-makes-it-into-new-research-presentation/
Nevertheless, the XB1 may be an evolution of drawbridge or might be an outright departure and based on other research.