The ghosts in both dramas want to settle their unfinished business on earth before they move on. They both discover that they can possess a person. While they use the person that they possess to find about their deaths, they also help them improve their life.
The male leads of both dramas suffer from Prosopagnosia, a face blindness condition. They try all ways to recognize people in their own ways, but they get help from their secretaries. The stories are totally different but they are both enjoyable, full of humour and great romance.
The Ghosts from both dramas cannot remember their pasts and why they died. They get to know later on in the story and why they could not go to heaven, reincarnate, etc.
Both dramas receive messages from the future. The story and why they receive the messages are different.
Definitely continue watching the second season because it is great! :)
They are both adaptations of the manga, however the chinese version is longer.