Hey Luccheno,
I'm happy to answer. When you think of a typical "game engine" you think of the set of libraries used to perform model/terrain/water/particle rendering, camera movement, animation, physics, user input, and sound. These are all, in general, things that the user experiences directly on the client-side and defines the "look" and somewhat the "feel" of a game. For these things we're using the CryEngine.
In contrast, there are a set of services/libraries running on the back-end that drive the dynamic story engine. These servces are scanning for and initiating dramatic situations and controlling the hierarchical, goal-based AI of the NPCs. These services also define the rules/mechanics which make Chronicles of Elyria different from other games that use the CryEngine. This collection of server-side logic and services is the Soulborn Engine.
The full set of features which are provided by the Soulborn Engine will be revealed over time through developer journals and from answering questions here on the forums.
Cheers!
Caspian