Bruno, from The Boy in the Striped Pajamas, is much younger than Helmuth, form The Boy Who Dared. Helmuth does not has a father, but Bruno does. Bruno's father is a commandant for the Nazis. They both want to be german soldiers when they grow up. They are both somewhat oblivious to what is happening in the world. Bruno is free and not under captivity, but Helmuth is in a jail cell. Helmuth and Bruno are both brave german boys. However, Helmuth is seventeen and Bruno is only nine.
Bruno is motivated by his friendship with Shmuel, but also by his hatred of Lt. Kotler. Helmuth wants to become a Hitler Youth to make his mother proud. Bruno's passion for exploration is why he help look for Shmuel's dad, but it is is also what gets him killed. Bruno thinks that Adolf Hitler is rude and has bad manners, but Helmuth just hates him.