Murder?

Maybe the US has a different legal definition for it, but I understand manslaughter and murder to be two different things with the highest manslaughter charges usually being as severe as those of murder.

The definition of manslaughter differs among legal jurisdictions, however is generally differentiated from murder based on the state of mind of the defendant, with the level of culpability for manslaughter decided on the presence or lack of reasonableness and negligence in their actions.

Loosely, it looks more at intent. Could be the same recklessness and negligence that causes death, but causing death was something ignored rather than intended.