It was really just two bonus episodes that theoretically could have been something that was cut and didn't make it into the final show. Also, for you to keep an eye out for it, I liked the cute little detail of the paintings in the student council room being different. If you liked Angel Beats and want some more episodes with these characters, it's a good watch. It lives up to the same quality of the rest of the series as just an extra two episodes. Due to them being extra episodes, there's not really hard-hitting drama or anything, but they're still goodwatches that are worth your time.