Batman and Bruce Wayne both have different personalities.

Batman, in most of his incarnations, is a dark and grim hero with a personal vendetta against criminals. Traumatized by the death of his parents, Batman has sworn to rid Gotham from the criminal elements that took his parents from him. He is very paranoid and obsessive, which often makes it difficult for him to trust other people that aren't Alfred, the Robins, or the Batgirls.

Despite this, Batman has proved to have a great love for humanity, which was instilled by his parents. His father was a doctor, while his mother was a crusader against child abuse. Indeed, Batman's oath of vengeance is tempered with the greater ideal of justice. He refrains from killing, as he feels this would not make him any better than the criminals he fights. He is also a very prominent member of the Justice League and the founder of the Outsiders.

To protect his secret identity, Batman has constructed a fake persona he can use in his civilian identity. To the world at large, Bruce Wayne is a self-absorbed, superficial, irresponsible playboy and philanthropist. Only his closest allies know that this attitude is just an act.

The Bruce Wayne/playboy aspect of his character is a facade, while the masked and particularly dark, grim vigilante is marked as the "true" man. Usually, Batman is further separated from Bruce Wayne by the raspy and stony bass voice he usually assumes while costumed.