In Chapter 3, Calpurnia scolds Scout for looking down on Walter Cunningham Jr. Scout makes fun of the way Walter eats and Calpurnia takes Scout into the kitchen and tells her that Walter is company and she should treat him with respect. Cal adds that even if the Finches are "better" than the Cunninghams, it means nothing if she is going to be rude. Here, "better" is probably indicative of being better educated and of a higher social class. Cal believes that Scout should be kind to anyone, especially if they are company, regardless of class. Therefore, Cal believes that Walter should feel welcome in their home.
In Chapter 23, Scout claims that she is going to invite Walter to spend the night. Aunt Alexandra says Scout should be nice to Walter but she can not invite him to their home. Then Aunt Alexandra justifies her position by saying that Walter is "trash." Cal is clearly more tolerant and welcoming of people from different social backgrounds than Aunt Alexandra is. The two women do not disagree face to face, but they certainly have different opinions on this matter.
In Chapter 14, Scout tells Aunt Alexandra that she will visit Cal at her house someday. Cal had already said this would be fine. But Aunt Alexandra says no to this as well. Atticus replies that there is no harm in letting Scout visit Cal. Aunt Alexandra even claims that Cal is no longer need at their home, now that she is living there. Atticus vetoes this as well.