Windows / Android / iOS

Unlike iOS or Windows, Android is a completely open-source mobile operating system based on a Linux kernel and released under the Apache license.
top android UI are - MIUI - Xiaomi , Realme UI - realme  , RedMagic OS -NUBIA
, ColorOS - Oppo , JOYUI BLACKSHARK (XIAOMI) , Magic UI , ROG UI

Windows is a group of several proprietary graphical operating system families, all of which are developed and marketed by Microsoft. 
Windows - XP , 7 , 8.1 , 10  , 11

(J2ME) Android smartphones run apps based on a version of Java. It is not directly compatible with other versions of Java, such as J2ME. J2ME has faded in popularity since the advent of smartphones, which can run much richer, more powerful apps than J2ME allows.

iOS, an acronym for iPhone Operating System, is a Unix-derived operating system powering all of Apple's mobile devices. 3 The name iOS was not officially applied to the software until 2008, when Apple released the iPhone software development kit (SDK), enabling any app makers to create applications for the platform. - iphones 

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