Android is an operating system for mobile devices such as smartphones and tablet computers. It consists of a kernel based on the Linux kernel, with middleware, libraries and APIs written in C and application software running on an application framework which includes...
Google Chrome OS is a Linux-based operating system designed by Google that uses the Google Chrome web browser as its principal user interface, so it works primarily with web applications.
iOS is a mobile operating system developed by Apple Inc. and distributed exclusively for Apple hardware. It is the operating system that powers iPhone, iPod Touch, and formerly iPad.
CloudReady is a operating system built and maintained by Neverware. Based on Google’s open source Chromium OS, CloudReady uses web apps and both cloud storage (Google Drive) as well as local storage (File manager). Comes without Android app support.
QtMoko is debian distribution for Linux based SmartPhones, like Openmoko Freerunner and Goldelico's GTA04 phone. Phone and user interface is based on QT Extendeded formerly known as Qtopia..
The project seems to be no longer developed. Last version, v58, released in December 2013, can be still downloaded from SourceForge.