Answer and Explanation:
According to the text, Sofia and Celie are each other's opposite. It is interesting to see that there is certain level of friendship between them in spite of the differences. However, that friendship is permeated by feelings of pity and envy resulting from their values, beliefs and upbringing.
Celie is clearly a religious woman who bases her own and her husband's behaviors on the Bible. She believes women should be obedient to their husbands and, apparently, that seems to justify violence for her:
"she used to feel angry but no longer does; after all the Bible says to respect your husband and your father."
However, such violence does have an impact on her. Otherwise, she would not feel jealous of Sofia and would not tell Harpo to beat her friend.
Sofia, on the other hand, is a strong woman who does not accept being mistreated. She has been strong and defiant her whole life. Even authority figures, such as her own father, would be fought against if she felt it to be necessary. No wonder she does not fear her own husband:
"The next time Celie sees Harpo, his face is covered with bruises. When she visits Harpo and Sofia [...] they are fighting like two men."