What is the difference between an iOS app, Android app and HTML5 (Mobile Website)?

iOS app – used with Apple iPhone and iPads
Android app – used with Samsung, Google, HTC and many other devices. Basically, all non-Apple devices.
HTML5 Mobile Websites – you are able to view the app content on a mobile device and the layout automatically adjusts to properly display in the mobile device you are using. However, because it is a webview, it does not possess many on the functionalities of an iOS or Android app. These would include interfaces with the device’s camera, GPS, calendar, Push notifications, etc.