If you're not familiar, the Discord overlay is a part of the desktop application that can draw on top of the games you play.

Trying to turn off the new game overlay that Discord automatically turned on in its latest update? Here's how. Discord has pushed out a brand-new update—if you haven't seen it yet, don't worry ...

Steam Overlay is a component of Steam that allows the user to use it on top of any game that you are playing. This won’t work for all the games, it can be only be used for Steam games.