In contrast to the dissolute, drunken, disreputable Bob Ewell, Tom Robinson is one of the figurative mockingbirds in Harper Lee's novel. For he is innocent of the aspersions cast against him by the town as well as the charges that the Ewells bring against him.
Because Bob Ewell, whom even the W.P.A. has had to fire, squanders his welfare check on liquor and neglects his motherless children, his oldest child, Mayella, must try to care for her siblings. When Tom Robinson walks past the Ewell place on his way to and from work, Mayella sometimes stops him, asking if he will help her with heavy things. One day, when she asks Tom to break up an old "chiffarobe," he kindly stops. However, in her loneliness Mayella has other intentions, and she kisses Tom.
Unfortunately for Tom, Bob Ewell returns home and catches Mayella in her ruse. Bob punches his daughter after a terrified Tom flees. Then, because Tom is a black man, Ewell brings charges of rape against Tom, lest anyone discover the truth. He has no regard for Tom as a human being; instead, he wants to make a name for himself and be certain the ni**** stays "in his place."
Bob Ewell has Mayella bring false charges of rape against Tom, and there is a trial at the county courthouse. Acting like a "bantam rooster," Bob Ewell thinks that the white people in town will appreciate his putting a Negro in his place.
While the people do not appreciate the Ewells' false testimony and know what "white trash" the Ewells really are, the jury nevertheless convicts Tom of rape. Despairing, Tom Robinson tries to escape from prison. He is shot repeatedly and dies while the shiftless and mendacious Ewells live.
Bob Ewell and Tom Robinson are very different people. Bob Ewell is scum in every way. He doesn't work, he's a drunk, he doesn't take care of his kids, in fact, he beats them, he probably sexually abuses them, too. The only thing he has going for him is his color. In the time and societal setting of the story, being a white man makes him socially higher than a black man. During Mayella's testimony, we learn a great deal about the Ewell family and particularly Bob Ewell and none of what we learn is good. Tom Robinson, on the other hand, is a hard-working conscientious man. Despite the fact that he has a useless arm, he works hard to care for his family. Seeing that there is no one to help Mayella Ewell, he even stops and does occasional chores for her. Tom is honest and upright. The only thing going against Tom is his color. That color alone determines where each of these men stands in society is the one thing that they do have in common.