Is Enlightenment a full DE or just a WM? I installed Enlightenment on my Linux Mint 17.2 Cinnamon. I thought it was just a Window Manager that I could switch to and use within Cinnamon. However, I found that I had to log out to my display manager and log in to Enlightenment. It presented me with what appeared to be a complete Desktop Environment. This brings me to the question: is Enlightenment a complete Desktop Environment or just a Windows Manager? Also, is it possible for me to use it to replace Muffin within Cinnamon? I doubt this is possible if Enlightenment is a complete DE.

Enlightenment is a Windows Manager but with additional features, however, Cinnamon does not currently have any sort of support for other Window Managers than Muffin (Cinnamons default one).

The reason you had to logout to use Enlightenment is not because it's "more than a Windows Manager". It's simply because it's not Cinnamon. So what you tried to do is to run two separate GUI environments on the same X server.