@Tamerlane
Then it is just considered manslaughter. While both manslaughter and murder both fall under homicide, murder is tied with intent, and almost always a more sever punishment. However, there are a few subcategories of manslaughter, voluntary (like if you killed in self defense, while protecting others, or in the "heat of passion") and involuntary (like a car crash from a DUI, being negligent, or being reckless) which can effect your sentencing.
Murder has a few sub categories as well, first degree, second degree, and sometimes third degree (though this one is only applicable in certain areas). The difference between first and second degree is if the murder was planed prior to is occurrence. First degree was a planned murder (like an assassination, or a hit).
There can sometimes, while unlikely, be a grey area with second degree murder, and voluntary manslaughter. Often involving "heat of passion", or killing resulting from a person being provoked, a rash act from intense emotion from being provoked, or the person was provoked in such a way that an average person would normally act rash.