There are two versions of Windows 10 Iot: Windows 10 IoT Core and Windows 10 IoT Enterprise. This tag should only be used for questions regarding Windows 10 IoT Enterprise. Windows 10 IoT Core has its own tag which should be used for those questions. The main difference between the two is that Windows 10 IoT Enterprise supports Win32 applications as well as WinRT and UWP. Windows 10 IoT Enterprise requires a paid license.
Windows 10 IoT Enterprise is an embedded device version of Windows 10 used with point of sale terminals and other devices which run software that requires more than what is offered by WinRT and UWP applications.
Windows 10 IoT Enterprise requires a paid license from Microsoft unlike Windows 10 IoT Core which is a free license and can be downloaded from Microsoft.
Typical uses for Windows 10 IoT is on small board computers such as the Raspberry Pi running single purpose applications such as a weather station.
See An overview of Windows 10 IoT Enterprise:
Windows 10 IoT Enterprise is a full version of Windows 10 that delivers enterprise manageability and security to IoT solutions. Windows 10 IoT Enterprise shares all the benefits of the worldwide Windows ecosystem. It is a binary equivalent to Windows 10 Enterprise, so you can use the same familiar development and management tools as client PCs and laptops. However, when it comes to licensing and distribution, the desktop version and IoT versions differ.