In addition to being similar in terms of pacing and overall tone, both dramas revolve around a male protagonist tasked with helping lost souls make peace with their mortal life to travel into the afterlife.
Mysteries surrounding the main character with mental issues and a big plot twist regarding main characters identity. Also tragic stories of supporting characters.
Both stories feature a psychologist who needs to explain away and deal with the supernatural appearances of ghosts. Both works have plot twists that are pretty much identical.