Both are pretty dark themed dramas about school bullying. In both dramas the main lead tries to change something with her positive attitude. While LIFE handles the bullying between students Angry Mom takes it even further. Both also have some comedic elements to relieve the dark theme of the dramas. Totally recommend both dramas !
Both dramas are similar as they highlight the difference an adult's influence can make in a child's behaviour and upbringing, although the nature of relationships shown in the two are different. Both feature strong female characters who will do anything for their respective children, and kind caring teachers who work with the main characters to get to the bottom of the mystery.