Windows Phone is a unique system. All three other systems are Unix-based. Apple iOS is based on BSD UNIX, Google Android is based on Linux, and BlackBerry 10 is based on QNX. Windows Phone 8/8.1, on the other hand, is based on Microsoft Windows, and shares its system architecture and the file system (NTFS).
Windows Phone 8/8.1 is a well-balanced operating system that learned a lot from Android and iOS. Somewhat similar to iOS, it offers the ability to create cloud backups (although these backups contain less information compared to iOS, with almost no application data being restored, save for login data). The OS features separate data space (sandbox) for each application and leaves no residual garbage after removing an app. However, it allows access to shared files (for example, music and videos can be played by any supported application and not just that one app the user imported the data to), which is similar to Android...