The story explores boundaries, both literal and figurative. Shmuel, young Jewish boy and Bruno, the son of Nazi commandant are separated by the fence and by the strict rules of Nazi, which forbids Germans to be friends with Jews.
On one side of the fence people live in comfort, they have food, wine but on the other side people are staving and the worst human cruelty is evident. The division and meaning of the division was well described (page 127) when both boys drew their symbols on the ground- the Star of David which represented the Jews and Nazi symbol on the other side, made the reader understand the literal