Both series are about an animal/insect turning into an attractive young man. They don't know how to properly act like a human and many situations take place as result.

Both series revolve around an animal/insect turning into a male human being to help a woman. A fluffy romance follows.

Both are about a group of high schoolers who grew up in the same apartment building and are now involved in a web of romantic/sexual relationships with dark emotions and motivations being rampant.

Both are dramas about someone needing an organ transplant for a family member. They meet someone with a terminal illness who is willing to donate. They must get married for the transplant to be legal but eventually end up falling in love.

Both series have a main character that is very smart and uses his intelligence to survive and win against others who are physically stronger than him. He also has a very care-free attitude and isn't afraid to bend the rules (or ignore them altogether) which gets him into some strange (and often times comedic) situations.

Both are about young women who by some strange circumstance become the focus of an unhealthy obsession of a rich and powerful guy.

Both series feature a young female character who ends up meeting a powerful older man and developing a unique relationship with him. Both women develop unrequited love for the elusive man and go through many trials because of their love.

Both dramas are about a teacher and student that somehow end up living together and must keep it a secret from others. They begin to develop feelings for each other.

Both series heavily feature medical aspects with there being a younger woman who enters the field to get closer to an older man that she loves.

Both series take place in hospitals with the main character pursing a career in medicine to aid/get closer to their crush.

Both shows showcase people from different countries and their opinions and experiences on topics based on their cultures and how they view and differ from Korean culture.

Both dramas are about one of the leads falling in love with the other when they were younger and being reunited later on after the female lead has gained/lost weight. Her changed appearance also leads to mistaken identity/not remembering the other from before.