In what sense do Bruno and Shmuel disagree about the soldiers?

In chapter 13, Bruno and Shmuel have a rare disagreement. The subject of soldiers is a sensitive one, and neither boy can find common ground with the other. In other words, Bruno and Shmuel disagree without reservation on the subject of soldiers. 

While Bruno believes that there are some good soldiers, Shmuel believes otherwise. Because of his experiences, Shmuel is wary of soldiers. Unlike Bruno, he has never met a soldier who treated him kindly...

In chapter 13, Bruno and Shmuel have a rare disagreement. The subject of soldiers is a sensitive one, and neither boy can find common ground with the other. In other words, Bruno and Shmuel disagree without reservation on the subject of soldiers. 

While Bruno believes that there are some good soldiers, Shmuel believes otherwise. Because of his experiences, Shmuel is wary of soldiers. Unlike Bruno, he has never met a soldier who treated him kindly or with any consideration for his humanity.

On the other hand, Bruno has never experienced explicitly cruel treatment from a soldier. His only conception of a good soldier is his father. Although Bruno's father remains a detached figure in his life, he does share a bond with Bruno.  As a consequence, Bruno thinks that his father is a shining example of a "good" soldier. Additionally, Bruno's father also dresses impressively, has the respect of his fellow soldiers, and the regard of "The Fury." Because of these factors, Bruno concludes that his father is a good soldier.

Of course, this is a very biased assumption on Bruno's part. However, Shmuel's assumptions are also biased: since he has only experienced cruelty from soldiers, he cannot conceive of there ever being such a thing as a "good" soldier.