Windows 10 IoT Core is a new edition for Windows targeted towards small, embedded devices that may or may not have screens. For devices with screens, Windows 10 IoT Core does not have a Windows shell experience; instead you can write a Universal Windows app that is the interface and “personality” for your device. IoT core designed to have a low barrier to entry and make it easy to build professional grade devices. It’s designed to work with a variety of open source languages and works well with Visual Studio.
Oh, and you can also use it to build robotic air-hockey tables.