Read the excerpts from chapter 2 of Night.

Excerpt 1

When they came back, they told us that they had learned, in exchange for a gold watch, that this was the final destination. We were to leave the train here. There was a labor camp on the site. The conditions were good. Families would not be separated. Only the young would work in the factories. The old and the sick would find work in the fields.

Confidence soared. Suddenly we felt free of the previous nights’ terror. We gave thanks to God.

Excerpt 2

We stared at the flames in the darkness. A wretched stench floated in the air. Abruptly, our doors opened. Strange-looking creatures, dressed in striped jackets and black pants, jumped into the wagon. Holding flashlights and sticks, they began to strike at us left and right, shouting:

"Everybody out! Leave everything inside. Hurry up!"

We jumped out. I glanced at Mrs. Schächter. Her little boy was still holding her hand.

In front of us, those flames. In the air, the smell of burning flesh. It must have been around midnight. We had arrived. In Birkenau.

How do the excerpts differ in purpose?

The first excerpt tells what is expected of them, and the second tells what happens to them.
The first excerpt indicates facts about the camp, and the second indicates lies about the camp.
The first excerpt shows their expectations about the camp, and the second shows the reality of their circumstances.
The first excerpt explains the conditions when they arrive, and the second explains how the circumstances change over time.