Moshe the Beadle is different for a couple of reasons. Initially, he is physically different. He looks physically different from the other people in Sighet. He has a physical limp and looks "physically awkward." As contrasted to the respect from others that Eliezer's father generates as a member of the community, Moshe does not command that level of respect, in part because of his physical presence.
Another reason Moshe is different is because of his spiritual dimension. The members of Sighet, like Eliezer's father, are based in commerce. They focus on the economic aspects of existence. Moshe is different because he has committed himself to the exploration of the spiritual. He is a mystic who takes the relationship with God extremely seriously. When he tells Eliezer that he wishes only to ask God "the questions," it is a moment in which Moshe shows his differences. Moshe is different in that his relationship with God is one that is profound enough to address the questions of existence with answers coming secondary.
Finally, Moshe is different because he is the first in the narrative to speak of the Nazi atrocities. When he describes hiding under a stack of dead bodies, pretending to be dead, and articulates what it was like to see babies thrown in the air and used as target practice, Moshe's difference is illuminated. Moshe is different because he sees the atrocities that will await all of those in Sighet. The fact that Moshe is received with disdain and mockery reflects how his experiences make him fundamentally different than the other people of Sighet.