Windows Phone 8 shares a lot with Windows 8. They both use the new WinRT runtime. But, as weird as it sounds, they have sometimes differences where you wouldn’t expect.
Example, if you want to detect if you are in design mode (like in Blend our the VS designer) in Windows 8, you do :
While in Windows Phone 8 you do :
Smells like two teams that didn’t talk to each others 😉