Glitch: In video games, a glitch is a programming error which results in behavior not intended by the programmers. Glitches may include incorrectly displayed graphics, collision detection errors, game-freezing or crashes, sound issues, and others. Some glitches are potentially dangerous to the game save data.
Bug: A software bug is an error, flaw, mistake, failure, or fault in a computer program that prevents it from behaving as intended (e.g., producing an incorrect or unexpected result). Most bugs arise from mistakes and errors made by people in either a program's source code or its design, and a few are caused by compilers producing incorrect code