Both dramas are high school teen stories with love triangles and high school drama. While Failing in Love is a more coming of age story with a little more realism doing a great job in portraying the complexity of being a teenager. Best Mistake is a more fluffy, fun to watch and doesn't really have a deeper message but it is nice to binge-watch.
Both dramas are quite short and have great actors! They both are part of the coming of age genre, with similar storylines as both are about high school students and the struggles of studying and in general the struggles of being a teenager. Also, both dramas finish with an open-end, living the watcher to draw her/his conclusions.