Manslaughter refers to the unlawful killing of one human being by another without malice aforethought. Murder, on the other hand, refers to the unlawful killing of one human being by another with malice aforethought. So, what is this 'malice aforethought' which differentiates manslaughter from murder? In legal terminology, 'malice aforethought' refers to the intention to kill or harm. Hence, if the unlawful killing is premeditated, it amounts to a murder. If not, it amounts to manslaughter. If Mr. X takes Mr. Y atop a high-rise building and pushes him to death, it amounts to murder. In contrast, if they get into an altercation on a staircase, wherein Mr. Y abuses Mr. X and, in turn, Mr. X slaps Mr. Y, who falls from the stairs and dies, then it can be considered manslaughter. As for homicide, it is defined as the deliberate and unlawful killing of a human being by another, and therefore, both manslaughter and murder are considered homicides. Having said that, things are not as simple as they seem; at least, not in the field of law. There are some specifics that need to be considered when understanding whether the said act is manslaughter or murder. Before we get to the details of these two concepts, let's get well-versed with the concept of homicide, which happens to be an umbrella term for the two. Like we said before, homicide is the act of a human being killing another human being. The term is derived from the Latin word, homicidium, which, in turn, is the combination of two words, homo meaning human being, and caedere, meaning to cut or kill. Though it is often used synonymously with murder, it is not restricted to the same. Murder is basically a form of criminal homicide, so is manslaughter. There do exist cases of non-criminal homicide, wherein the act of killing is considered justified or excusable. For example, a person killing another in self defense, or a law enforcement officer killing someone in the line of duty. It's the intent that helps to determine whether a particular act of homicide was manslaughter or murder. If the person hits someone with the intention of hurting―not killing, but unintentionally ends up killing him, then it is considered manslaughter. Similarly, when the person acts on being provoked, or when he is not in a sane frame of mind because of underlying psychiatric health issues, then homicide amounts to manslaughter. As the person's state of mind is not entirely in his control in such cases, the act of killing is not considered a murder. An act of homicide is considered a murder when it is deliberate and premeditated. In this case, a person unlawfully kills another person after proper planning and plotting. An apt example would be a case wherein, following an altercation, a person goes and buys a gun, returns to the person with whom he had the altercation, and kills him. Even the intent to cause severe injury, which eventually results in the person's death, or an act which shows utter disregard to human life, eventually resulting in a death, are considered equivalent to intent to kill, and thus, such acts fall in the ambit of murder. Voluntary and Involuntary Manslaughter Manslaughter can be voluntary and involuntary. In the case of voluntary manslaughter, the intent or 'malice aforethought' is there, but the act, i.e., the unlawful killing, is committed in the 'heat of passion' in response to a provocation which is strong enough to make a reasonable person to lose control over himself. If, however, there is enough time for the defendant to cool down and then he commits homicide, then it is considered a murder. Involuntary manslaughter includes gross negligence manslaughter, wherein a person kills another person because of negligence or recklessness on his part, without intending to do so; constructive manslaughter, wherein a person causes a death as a result of some unlawful, dangerous act on his part; and vehicular manslaughter, in which case the death is caused as a result of negligence while driving. The case of Conrad Murray, Michael Jackson's personal physician, is an apt example of involuntary manslaughter. First-degree and Second-degree Murder As with manslaughter, even murder is classified into two types: first-degree murder and second-degree murder. Whether an act of homicide will be considered a first- or second-degree murder will depend on the circumstances and the area of jurisdiction. As the intention to kill exists in both cases, it usually comes down to whether the act was premeditated or not. Excessive planning is involved in first-degree murder, such that the person may even go to the extent of using explosives, or resort to other sophisticated technique to commit the crime. Also to be taken into account is the felony murder rule, which states that any death that occurs during a felony―even if it's that of one of the felons―is considered a murder. At times, there is a thin line of difference between murder and manslaughter, such that everything comes down to subjectivity. Let's say, for example, Mr. X accidentally bumps into Mr. Y while walking on a crowded street, but continues to walk instead of apologizing, and a furious Mr. Y takes out a gun and kills him. In this case, despite the 'provocation', Mr. Y will be charged with murder, because the 'provocation', as we discussed before, was not strong enough to make a reasonable person to lose control over himself. A strong provocation, as seen in several cases, is adultery. Though both are considered criminal offenses in the U.S., a murder is definitely more serious than manslaughter, and that reflects in the sentencing as well. While a person convicted for murder can be sentenced to life in prison without the possibility of parole or even death in some jurisdictions, a person convicted for manslaughter will be sentenced to imprisonment. But obviously, voluntary manslaughter will result in a relatively severe sentence. If, however, the defense fails to establish adequate provocation, the person who is being tried for manslaughter, can be tried and subsequently sentenced for murder.