Diegetic vs. Non-diegetic Sound

What is the difference between diegetic and non-diegetic sound?  What is an example of each that you can think of from a film?

    Diegetic is anything that comes from within the story, i.e., dialogue, anything on screen, in-world music, and in-world sound effects. Non-diegetic is everything that is outside the story such as narration, external graphics, the cinematic score, and added sound effects. An example of a diegetic sound from a film I've seen before is the singing in Teen Beach Movie as the two protagonists acknowledge it and it serves as a part of the plot that they interact with, especially clear in the song Can't Stop Singing. An example of a non-diegetic sound from a movie I've seen is the score from Halloween as the characters in the movie can't hear it despite how it affects the viewing experience.