Why does Bruno think that Shmuel and face is strange?

Bruno thinks Shmuel's face is strange because he has never seen someone like him before, as Shmuel is wearing the striped pajamas associated with the concentration camp. This visual difference, coupled with the stark contrast between their lives, makes Bruno feel uneasy and curious. He struggles to understand Shmuel's situation, reflecting his limited exposure to the realities of the Holocaust and the lives of those in the camp. Ultimately, this moment highlights Bruno's innocence and naivety regarding the world around him.