While i will not say both dramas are same, co it's not. Each have it's unique blend of same little elements though.
The demon, immortal and human trio set to solve cases. Their interactions. From enemies to best friends. The case solving journey brings them closer understand their past stories.

Both the show's the vigilante and the devil judge revolve around the justice system, that is lenient towards criminals and strict against poor and victims. The main lead becomes devil to burn the existing devils himself.