And also any other class that has a “normal” version and a base version?
Look up in Class Viewer (Window->Development Tools->Class Viewer), GameMode inference from GameModeBase, in the past there was only GameMode, problem is if you have big base with lot of APIs already set you can’t change those APIs and how they are strcuture, or else oyu modify engine code or rewrite (does not matter if C++ or Blueprint) entire class which most likely won’t work with rest of engine code anyway. So Epic decided to pull some things from GameMode leaving it in GameModeBase and put what was thrown out to new GameMode which is child of GameModeBase, so developers (aspecially blueprint once) have better flexibility.
Best way see what GameMode includes to GameModeBase is to look in to the code
You don’t need to understand the code just look on functions names to have idea, you can also look up on API refrence you have a link to GameModeBase there too: