Windows is the only environment with desktop/tablet compatibility. Most Windows desktop/laptop apps can also run on Windows tablets. Starting with Windows 8, new lightweight tablets were a departure from earlier models (see
Tablet PC). See
hybrid laptop and
Windows tablet.
Phone/Tablet Compatibility
iPhone apps run in iPad tablets, and Android phone apps run in Android tablets. Using different methods, iPads and Android tablets can scale apps to fill the screen. Developers only need to create one version, and users with phones and tablets only have to buy one app. In many cases, however, separate phone and tablet apps are necessary. See
mobile device vendor control and
how to select a mobile device.
Windows Phone/Tablet Compatibility
Windows desktop and tablet apps are the same. When Microsoft was selling its phones, vendors had to publish both a phone and desktop/tablet app in order to support all Windows environments. Both phone and RT tablets are long gone. See
Windows Phone,
Windows RT and
Windows 8.
Desktop-Mobile Compatibility
Windows apps run on Windows 10 tablets, but Mac apps do not run on Apple's mobile devices (see
iOS).
Smartphone-Tablet Compatibility
Even if the same app runs in both phone and tablet, the chances are that a tablet version will be created to use the larger screen.