How does talking about Shmuel to Gretel help Brunno understand his friend?

Talking about Shmuel to Gretel helps Bruno gain a deeper perspective on his friend by contrasting their vastly different lives and experiences. Gretel's dismissive attitude towards Shmuel highlights the societal divide and prejudice that exists, prompting Bruno to question the injustices faced by Shmuel. This conversation encourages Bruno to reflect on friendship, empathy, and the innocence of childhood, deepening his understanding of Shmuel's situation. Ultimately, it reinforces Bruno's growing awareness of the moral complexities surrounding him.