@fmf said
How would you define the difference between retribution and vengeance?
Some modern dictionaries and current usage may consider the two words to be equivalent. However, I would cite Webster's unabridged dictionary (that's the big fat library edition) as the definitive reference for what proper (American) English would still recognize to be a legitimate and useful distinction between the two:
"Vengeance: punishment inflicted in return for an injury or an offense; retribution; often, also, passionate or unrestrained revenge. Etymology: from old French "vengier", cf vendetta."
"Retribution: 2. the dispensing or receiving of reward or punishment according to the deserts of the individual. Etym. from Latin retributio."
From these two definitions, it follows that "vengeance" is related to the motive (or passion) of the aggrieved avenger, whereas "retribution" is related to the (objective or legal or moral) desert of the receiver without regard to the motive or passion of the distributor.
Among civilized peoples, punishment is meted out by a dispassionate civil authority (i.e, the court system in a Rechtsstaat). Among primitive peoples and the Mafia, punishment is meted out by the aggrieved party or his family (e.g., blood feuding, honor killing). The former typifies retribution, the latter vengeance.