Windows NT 4.0 Embedded is a special edition of Windows NT 4.0 aimed at computer-powered appliances, vending machines, ATMs and other devices that can't be considered computers per se. It's the same system as the standard Windows NT 4.0, but it comes packaged in a database of components and dependencies, from which a developer can choose individual components to build customized setup CDs and hard disk boot images.
Windows NT 4.0 Embedded has been discontinued. Its successor is Windows XP Embedded.