This is a comparison of Windows Phone 7 vs Windows Mobile 6.5. They are very much different, complete opposites. In WinMo, you can customize your experience with a custom ROM or interface, plus you can change almost any aspect of the interface. In Windows Phone 7, you are limited to the interface that it comes with out of the box...you can't even change the browser or the keyboard. Also, WinMo is notoriously unstable unless you have the perfect ROM with performance tweaks. In Windows Phone 7, everything just works.