“Batman, when his parents were killed, began his life-long quest for Justice and/or Vengeance, depending on iteration. He studied, fought, and beat his way back to the world he vowed to reform. Fundamentally, Bruce Wayne was broken and shattered, and pieced himself back from the fragments.
“Green Arrow, on the other hand, has a very different story. He was an actual playboy, what Bruce pretends to be, for most of his life. When he was stranded on Starfish Island (comics) or Lian Yu (TV show), his former life fell apart. Everyone thought he was dead, and he had no way off the island. In both, he was forced to survive, got his skills, etc. out of necessity. When he later encounters a group doing something he knows is wrong, he realizes he has the skills- And therefore the obligation- to do something about it.
“Bruce threw away his life and reforged himself into a weapon for Justice. His stories are about revenge, justice for past crimes, and balancing the line between Hero and violent Vigilante.
“Oliver had his life thrown away, and was reforged into a tool of heroism. His stories are about second chances, vindication, and defending the wall between the darker sides of the world and its innocent civilians.”