What is the difference between Revenge and Justice as it relates to the events of the play 12 Angry Men?

Revenge would reflect a determination that the defendant is guilty based upon a juror's own bias, prejudice, and experience. Over the course of the play, a number of the jurors are prepared to convict the boy for no other reason than their own personal biases.

Justice, what the judicial system hopes to accomplish, requires that jurors reflect only upon the matter at hand. If you cannot walk into a jury room free of preconceived notions..... you shouldn't be there. A jurors vote should be cast using the evidence that is presented.... and only that evidence.