What's the difference between a murder and an assassination? [closed]

I am unsure what the technical difference is between a murder and an assassination. Instinctively I feel it's to do with the victim - perhaps their fame? Royalty?

What is the distinction between the two?

Yes, assassination is used to refer to a known person, often a political figure.

Assassination:

Assassination is the murder of a prominent person or political figure by a surprise attack, usually for payment or political reasons.

Murder:

The unlawful killing of one human by another, especially with premeditated malice.

The difference in meaning comes from the origin of the word, assassin (n.) 

1530s (in Anglo-Latin from mid-13c.), via French and Italian, from Arabic hashishiyyin "hashish-users," plural of hashishiyy, from hashish (q.v.). A fanatical Ismaili Muslim sect of the time of the Crusades, under leadership of the "Old Man of the Mountains" (translates Arabic shaik-al-jibal, name applied to Hasan ibu-al-Sabbah), with a reputation for murdering opposing leaders after intoxicating themselves by eating hashish. The plural suffix -in was mistaken in Europe for part of the word (compare Bedouin).

An assassination is the targeted killing of a specific pre-arranged person. It is especially used in cases where the target was a prominent public figure, and when the motive was political or ideological, but is not restricted to either.

Murder has been used to cover various deliberate acts of killing that were considered dishonourable or unjust in various ways, which has had various legal definitions over the course of history (e.g. it was once only applicable to a secretive killing, but saying "everyone saw, and he was awake and facing me" will not mean you only have to pay a fine today!)

As a legal term the precise definition varies according to jurisdiction, but generally includes a degree of premeditation, and a lack of justification (such as self-defence or act of war). Note that the premeditation may not necessarily be of the killing itself; e.g. in many places if you kill someone in the course of a premeditated armed crime, it is considered murder, though you did not intend to kill when you planned the crime. In general use, it remains a term applied to any killing that the speaker condemns.

As such, many assassinations are murders, and vice versa, but not all murders are assassinations (a bombing intended to cause terror, or the killing of a security guard who happened to be the guard on duty is not an assassination), and not all assassinations are necessarily murder (the targeted lawful killing of a specific combatant during war) and some are debated (whether the above case should be allowed by the rules of war is debated, and whether something was an act of war or of terror might also be).

As others have pointed out, the dictionary definitions suggest that "assassination" is usually associated with a well-known victim. But I think there's a clearer way to distinguish how the two are used in common parlance:

"Assasination" is almost exclusively reserved for murders in which someone is being killed primarily due to their title or role in an organization or movement.

Most typically, it's because they are the head of the entity in question (like a head of state, or the leader of an uprising), but not necessarily.