Whether an act of killing should be termed "assassination" or "murder" hinges on a number of facts. Often, the identity of the victim is crucial in making the assessment, as is the motive for the killing and the individual who carried it out. A variation in anyone of these three elements -- victim, motive or killer -- can mean the difference between the act of murder and the act of an assassination.
One definition of assassination contends that it is the act of killing someone with fame or notoriety. Important to this definition is the motive behind the act. Hitting a celebrity or elected official with a car is a tragic accident while hiring someone to shoot a celebrity or elected official is assassination. Unlike other forms of killing, the killer typically has an ideological motive or political motivation, either real or imagined. At times, the individual carrying out the act is deemed insane and has conjured one motivation or another. However, not all assassinations carried out by a killer are done for ideological or political motivations. Contract killings, or murder-for-hire, involves assassination for money.
The definition of murder can vary by jurisdiction. Generally speaking, murder is distinguished from other types of killings, such as manslaughter, from the presence of malice aforethought. Malice aforethought reflects a state of mind, whereby the killer displayed premeditation or thought and planning. In some jurisdictions, this concept is broadened to include a simple intent to kill, inflict severe bodily harm or carry out a dangerous felony. In the United States, murder is organized by degrees, with each degree signifying the absence or presence of some element.
First Degree Murder
In the United States, murder in the first degree is generally the unlawful killing of a human by another human in an act that is both willful and premeditated. It is often termed "lying in wait." Certain acts are treated as first degree murder by virtue of their character. They include strangulation, poisoning and anything that involves the actual lying-in-wait to commit the act. It is important to note that these are legal definitions. An act of killing premeditated killing by a civilian would be treated as first degree murder, though technically an assassination as well.
Second Degree Murder
U.S. state law tends to treat second degree murder as an act of killing carried out with the absence of premeditation. It is often carried out in the heat of passion or as an act of impulse. It is often seen as the middle ground between first degree murder and manslaughter, where death was not the intention.