In Windows 8, Universal Applications work in fullscreen, while in Windows 10, those apps work as normal software applications in a normal window. Windows 10 introduces Universal Windows Platform, a platform on which developed apps can work in all Windows 10 devices. According to Microsoft, Windows 10 is based on 'software as a service' model in which the operating system receives ongoing updates rather than issuing a full new version.
Windows 10 is an operating system as a service for consumers and businesses. Windows 10 (the successor to Windows 8 / 8.1) was released for the first time to public on July 29, 2015, it was available for many device platforms like desktop / laptop PC, smartphone, tablet etc., and it uses the same software ecosystem in all platforms.