In the context of Titanfall 2 technical discussions, these terms often relate to:
Titanfall engine branch - Valve Developer Community
There is an active modding community that uses tools to inject custom models or textures into the game's VPK files.
The game runs on a heavily modified version of the Source Engine (sometimes called the "Respawn branch"). "Deep features" in this context often refer to advanced rendering techniques like TSAA (Temporal Anti-Aliasing) or HBAO+ .