How is Scout (being ridiculed) discriminated like Boo Radley (being ostracized) and how she not?
How she isn't discriminated against is easier (and a bit more boring) to discuss. Scout is Caucasian (white), so she is not discriminated against racially. She is also the daughter of a well respected member of the city of Maycomb. By extension, she is given a lot of that respect as well.
Scout doesn't entirely escape from being ridiculed and ostracized, though. Her Aunt Alexandra is especially hard on Scout for not being lady-like enough. Aunt Alexandra is even able to get Atticus to have a sit down with Scout and ask her to be more ladylike.
"She asked me to tell you you must try to behave like the little lady and gentleman that you are."
To Scout, that's basically the end of the world. She is a tomboy through and through, but even her brother, Jem, starts to ostracize her for her behavior.
“It’s time you started bein‘ a girl and acting right!"
In chapter 12, Scout starts noticing some changes in Jem, and he tells her to start acting like a girl. Previously, he ridiculed her for acting like a girl, but now he wants her to act like it. Scout also noticed that Jem was less likely to go out and play with her as he previously did. It's like he couldn't be bothered by his little sister anymore.