Assassin's Creed Unity, a "Stealth Kill" refers to a silent assassination where you sneak up on an enemy from behind and quickly dispatch them with your hidden blade, usually without alerting nearby guards; while an "Epic Enemy Take down" is a more dramatic, sometimes flashy maneuver where you might use the environment, like leaping from a rooftop or utilizing a distraction, to take down a target in a visually striking way, often involving multiple enemies or a high-profile target.
Assassin's Creed Unity Stealth Kills and Epic Enemy Take downs