Although Tom is a conscientious and hard working man despite having a
bad arm and being subject to racial hatred, Bob Ewell- an unemployed drunk who beats and probably
rapes his children is at a societal advantage because of his skin colour.
Juxtaposes Bob's vulgarity to show just to what extent prejudice effected Tom's trial and verdict.
Tom Robinson is essentially the symbol of the mockingbird and the reason behind
the quote 'it is a sin to kill a mockingbird'. He is kind and attempts to bring
happiness to a white woman- and is even brave enough to suggest that he could
have done something to help her out. Whereas Bob beats and rapes her and
consumes copious amounts of alcohol.
Bob is embarrassed and angry when he's exposed as a liar at Tom's trial.
Bob Ewell is a violent racist, whereas Tom is unprejudiced and offers to help Mayella.