Within the context of ENIGMA, "end user" can be an ambiguous term. By definition, it means a person who uses a product. But what is "the product" and where is "the end"?
The product could mean ENIGMA itself, and an end user is the immediate user of the product (so a person using ENIGMA to develop a game or program). But that's not the end of production - then you have the Game or Program user.
The other case is that the end user is the person who plays the games or uses the programs designed with ENIGMA.
Even beyond that, you could have a program developed in ENIGMA which users can then use to, say, create a website, and then they will themselves have users who use the website. The end-user here could be three levels below ENIGMA, and soon enough it's turtles all the way down.
Because of this ambiguity, try to be clear about which user and end-user you are talking about. Even ENIGMA itself can have two end-user license agreements (EULA) - one for the game developer, and (as part of GPL) one that must be attached to the games developed within ENIGMA (which is pretty much completely open - you will always be able to license games developed within the official ENIGMA under whatever license you choose, even closed source and proprietary).