Dee and Maggie are both loved in a way by their mother, though she clearly starts out favoring Dee. Dee is the independent, strong daughter who has gone away to make something of herself. The mother loves the stories that she can tell and admires her ability to pursue she dreams and do something different with her life. Their relationship is based on a sense of pride and awe that her mother receives from the life that Dee lives. As the story progresses her mother realizes that she has put Dee on a pedestal unjustly, and that Dee's exciting life has made her superficial and vain.
Maggie is the constant daughter who is always there. Her mother knows that she can rely on Maggie to be there, and takes advantage of that fact. Maggie is simple and open, and her mother treats her as if she is bored with her. In the end, her mother realizes that she has overlooked Maggie's love and loyalty, mistaking her constant presence for simplicity rather than love and devotion.