The plots are both centered on odd and quiet high school boys. They both have eerie tones to them, but M. Boy is more gore horror, SCW is more realitistic and dark.
Both movies are about students that are severely bullied, bringing them to their breaking points. There's gore in them both and they have creepy tones.
Both films show a highschooler who is being severely bullied and who later seeks revenge. He finds some small comfort in a girl he likes until the bullies begin to get her involved.