This is an interesting topic because while the settings are completely different (Southern United States vs. South Africa) the themes have much in common.  Both novels ultimately center around a crime and the subsequent trial of a black man who is accused doing wrong to a white person.  In To Kill a Mockingbird Tom Robinson is accused of raping a white woman, but the audience knows very clearly that he is innocent of the charges.  In Cry, the Beloved Country, Absalom is accused of the murder of Jarvis and he admits to his role in the crime.  In each of the novels, there is a trial and in both cases, the young black men have EXCELLENT legal representation.  Atticus does a superb job in his defense of Tom, but the guilty verdict comes down because of the inherent racism of the time and place. Absalom has an excellent and very fair minded lawyer who does the best he can, but the letter of law has no choice but to find Absalom guilty, even though there are other defendants in the case.  Both men ultimately die -- Absalom is sentenced to death; Tom dies in a vain attempt at escaping prison -- an act that he had to have known could result in his death.  Race plays a much more significant role in the crime and trial of Tom Robinson than in that of Absalom, but the situations that get the men in trouble in the first place are very race driven -- Tom is accused because it is easy to accuse a black man and it is a "face-saver" for Mayella and Bob Ewell.  Absalom is robbing people and ends up killing Jarvis because as a young black man he has no economic prospects and is running around with the wrong crowd.

Another common element between the novels is that the aftermath of the crimes and trials has a positive affect on those around.  As awful as the deaths of the two young men are, a change in attitudes about race come about.  Jarvis's father is moved to better understand his son and he ultimately tries to help the native black people in his district by bringing in agricultural experts to help the people learn better farming methods.  The mere fact that Tom Robinson's jury actually spent a good amount of time before coming back with the guilty verdict is small victory and a small sign that the attitudes of white people towards blacks is changing.