In both cases, you perform an illegal act; you end up taking someone’s life! When you `murder’ someone, the act of killing the individual is deliberate or intentional. Usually, it is planned, and is carried out in a cold-blooded manner. It is for this reason that the punishment for murder is very severe. In the case of manslaughter, the act of killing may or may not be intentional. You could end up killing someone quite accidentally. If your kill your aunt or uncle because you want their property, then it is murder. If you run over a pedestrian, it is manslaughter. When you kill someone in self-defence, it is manslaughter, and not murder.
*The murders in Noida have upset many people in our country.