Both star Lee Sang Woo. Both deal with perverted individuals and sexual abuse.

Both show Choi Jae-Sung playing a gay/bi guy from the military. Both are LGBT.

Both films star Lee Sang Woo. Both show gritty homosexual interactions and military abuse of power.

Both films star Lee Sang Woo. Both show gritty homosexual interactions and military abuse of power.

Same actors, same director, same gritty violence and sexuality. Both show sexual abuse in the South Korean military, as well.

One of the short films in "All About My Father" depicts the same type of sexual abuse in the South Korean military as is shown in "Black Stone"

Both films show a lonely/shy dude making friends with the popular guy in school. He is then subjected to jealousy from the popular guy's groupees.

Two people forming a friendship that is strained because of one person's being severely bullied.

same actors same director.

Both films tackle abuse subordinates suffer in the military at the hands of their superiors.

Both films show a closeted gay man falling in love with another guy. He decides to get married to a woman, however, breaking his lover's heart.

Both these films seem to want to portray the importance of not letting love escape your grasp. They both show a closeted gay man falling deeply in love with another dude.