When Bruno states that he and shmuel are like twins why does shmuel reply a litlle bit?

Shmuel replies "a little bit" because, despite their close friendship, he is aware of the significant differences in their backgrounds and experiences. While they share a bond and a sense of connection, Shmuel's life as a Jewish boy in a concentration camp starkly contrasts with Bruno's sheltered existence. This response highlights the complexities of their friendship and the harsh realities of the world around them.