Android is mobile operating system by google. Android is designed primarily for touchscreen mobile devices such as smartphones and tablets. Android is also used on game consoles, digital cameras, PCs and other electronics.
iOS is a mobile operating system for Apple-manufactured devices. iOS runs on the iPhone, iPad, iPod.
Ionic apps run with a mixture of native code and web code, providing full access to native functionality if necessary, with the bulk of the UI of the app built with standard web technology.