Both have the same mysterious characters giving off a strong antagonistic vibe during the beginning (Lee dong sik played by shin ha kyun and Kang yohan played by jisung), the show really uses manipulation so well, the cinematography and the soundtracks are the key narrators. In short, both shows have the same dark environment and twists and turns that keep you on the edge of your seats.
The plot falls on a different angle but the execution of the plotline is almost identical.