The climax in The Merchant of Venice is a bit drawn out, but it centers around Portia's verdict which frees Antonio and sentences Shylock. In To Kill a Mockingbird, there are two climaxes: one is Tom Robinson's trial and the second is the encounter and aftermath of Bob Ewell's attack on the children. Comparing the two trials, we have very different outcomes. The legally bound but morally innocent Antonio is set free and Shylock is convicted: everyone lives happily ever after except Shylock. In Mockingbird, the innocent man (Tom) is convicted and ends up being killed while trying to escape. So, clearly the difference here is that in Shakespeare's play, things work out well (ironic considering how many of his plays end with multiple deaths). But in Mockingbird, the innocent man loses.
Bigotry plays a role in both works. Tom is accused and convicted because of people's racist beliefs. Although his actions toward Antonio are immoral, Shylock is also the victim of bigotry because he is Jewish. This racism and antisemitism both factor into the verdicts/climaxes.
To Kill a Mockingbird's second climax does resolve in a happy ending. Bob is killed and Boo (the other innocent man/mockingbird) is the hero. A key difference with this resolution and the resolution in Merchant is that Scout learns to see/understand things from the perspective of people different than her. In Merchant, this moral (in terms of bigotry) does not seem to come up. It is worth mentioning that the two works were written in different times and different genres. The courts are run differently, with Maycomb's court appearing more realistic because it is more modern.