In "Everything That Rises Must Converge," what are the similarities and differences between these two mothers and two sons?

In terms of differences, Mrs. Chestny and Julian, her son, are white. They, apparently, come from a family that used to be somewhat wealthy, as Mrs. Chestny is proud of the fact that her family once owned a plantation and two hundred slaves. In contrast, Carver and his mother are black. While Mrs. Chestny is relatively at ease and comfortable on the bus, especially before any black people get on, Carver's mother wears an expression that broadcasts the message, "Don't tamper with me." In fact, "Her face was set not only to meet opposition but to seek it out." Carver's mother seems prepared to do battle, while Julian's mother is, to Julian, irritatingly serene, even social. She begins "a general conversation meant to attract anyone who felt like talking." It seems clear that these two mothers have been treated quite differently in their lives: one has been privileged, while the other has not. One expects to be met with peace, whereas the other expects to be met with offense. Further, Julian has just graduated from college, while Carver is a young boy; it is likely that their mothers are likewise separated by age.
In terms of similarities, the most obvious one is that Carver's mother gets on the bus wearing the exact same hat that Julian's mother recently purchased. Ironically, the sales lady actually told Mrs. Chestny that she would not "meet [her]self coming and going," meaning that the hat is somewhat unusual (and implying that it is somewhat special—a notion that would seem to gratify Mrs. Chestny). It will set her apart. Ultimately, however, it is a symbol of how the races have begun to "converge"—as the title acknowledges—and how Mrs. Chestny is not alone in her ability to purchase such a hat. Carver, the child, is immature, playfully pushing his mother's buttons and eliciting a reaction from her. Likewise, Julian (though he is much older) is also immature, though he viciously pushes his mother's buttons in order to teach her a lesson.