Crashes that happen only in release mode builds character.
A configuration is a possible setup of compiler and linker options used when building a target. Configurations is the name used for it in Visual Studio.
The version used by programmers trying to find bugs. Debug info on, no profiling, logs everything and slow as a turn based game.
The normal version used for development. Debug info on, profiling on and logs the important things that does not slow down things.
The bleeding edge release version. Used by QA in development. Everything for speed and minimal size is on. In windows it is nice to have debugging also and store away the pdb's.