Think about the three families Bud has met so far in the story, the Amoses, Deza Malone and her mom, and Mr. Lewis and the sleets. What makes these families different from one another?

One difference between the families is their financial situation. The Amos family is presented to readers as quite rich:

Even though Todd was a puffy, rich old mama's boy who wore a robe and slippers . . .

The Malone family is the poorest of the three families. They do not even have a place to call home. They, like many other people during this time period, are forced to live in a shantytown. The Sleet family is the middle of the other two financial situations. They have a home and a stable income, but they would not be classified as rich.
In terms of their treatment of Bud, the Amos family is the outlier. Their attitude is that they rescued Bud, and he should be forever grateful for their saving graces. Because of this attitude, they believe that Bud should behave as a perfect little angel. In one scene, Mrs. Amos yells,

How dare you! This is how you choose to repay me? Not only have you struck him, you have provoked his asthma!

Mrs. Amos is definitely duped by her son into thinking that Bud is the instigator of the fight, but it is clear that she never considered Bud as a potential member of their family. She's "rescuing" him for one reason or another. When Bud doesn't fit her conceptual mold, the Amoses throw Bud into the shed like any other piece of equipment:

"Boy," Mrs. Amos said, "I am not the least bit surprised at your show of ingratitude. . . . Mr. Amos will show you to the shed tonight and you can come back in tomorrow for breakfast before you go."

The Sleets and the Malones are the complete opposite from the Amoses. The Sleets and Malones welcome Bud with open arms. They see a boy in need, and they take him in as he is. They aren't trying to rescue him or reform him. They are content with meeting him as he is, and both families immediately treat him as if he was a real member of their family. Bud never feels like an addition to those families. Instead, he feels included. Mrs. Sleet welcomes him to their home:

Now, while you wash up I'm going to go get some clothes that my boy outgrew a while ago, barely been used. So when you get dressed you come on down and we'll eat, you chose a great day to visit, we're having a very special breakfast today—pancakes, sausages and toast and a big glass of orange juice. You can meet Scott and Kim, too. How's that sound?

The Amos, Malone, and Sleet families each come from different social classes and treat Bud Caldwell differently when they meet him. The Amos family is financially secure but treats Bud with contempt. They are portrayed as strict and unsympathetic. Todd Amos bullies Bud by sticking a pencil up his nose and gets into a fight with him. Todd's parents also take Bud's suitcase and make him sleep in their shed. The Malone family occupies a lower social class than the Amoses and live in a Hooverville because they do not have a home. Despite their rough financial situation, the Malones are welcoming and hospitable. They allow Bud and Bugs to eat with them and provide the orphans a place to stay the night. After Lefty Lewis picks Bud up, he takes him to his daughter's home. Bud is introduced to the Sleet family, who are financially stable and welcome Bud with open arms. Mrs. Sleet gives Bud a fresh pair of clothes, a place to spend the night, and a home cooked meal. Her children also entertain Bud and are kind to him. Overall, the three families have different financial situations and treat Bud differently.