How does Scout's definition of "fine folks" differ from Aunt Alexandra's?
Aunt Alexandra bases her judgment of others on external characteristics such as social standing, income, family history, dress, and manners. This is evident from her constant efforts to change Scout's appearance, silence the children when they talk about black sheep in the Finch family, and in whom she chooses to invite to Atticus's house when she lives with Scout and Jem.
Scout, on the other hand, has blossomed under her father's wisdom and tolerance. She learns by the end of the novel to look at the internal. She bases her opinion of what makes somebody "fine" on observing how a person acts and by studying the motivation for his/her actions. For example, Scout portrays Heck Tate positively in her narration by telling of his warning Atticus about the mob of men headed toward the jail. She listens to and seems to understand Dolphus Raymond, the town outcast, when he tells the children why he acts drunk. She treats Boo Radley with dignity and respect at the novel's end when she realizes what he sacrificed for her and Jem by saving their lives. While Scout might not have perceived these characters as "fine" at the book's beginning, as she matures, so does her view of others.
Scout views other people as different since she has her father's values instilled in her. If she views someone she not only views them based on their external qualities, but also views their character. She treats Boo nicely as well as other people and wants to understand them. As Scout matures her morals allow her to judge someone based on their acts, not on their outside features.