What are differences and similarities between Tom Robinson’s trial in To Kill A Mockingbird and the Scottboros trials?

The two cases are extraordinarily similar. In fact, many scholars who studied the work assumed that the Tom Robinson trial was largely based on the case of the Scottboro Boys, though Harper Lee herself said that she was going for something "less sensational." Both trials include black men on trial for a crime that they did not commit and being convicted despite overwhelming evidence in their favor. Due to overwhelming prejudice, the defendants in both cases were written off before they even went to trial. Both cases even feature a pre-trial lynch mob. In regard to differences, they are not many. The first is that one of the accusers of the Scottsboro boys actually admitted to the fabrication of the story before the trial was over, though it did not help their case. Also, unlike Robinson, the Scottsboro boys had very poor legal representation.

The Scottsboro Boys were a group of young African American males wrongly convicted of the rape of two white women. The case took place in Alabama, the setting for To Kill a Mockingbird. Clearly, Tom Robinson's case is very similar to that of the Scottsboro Boys. In both cases, the prosecution had no hard evidence of guilt, relying instead upon blatantly fabricated stories. Tom Robinson and the Scottsboro defendants were effectively found guilty before they even appeared in court. At that time in the South, an accusation of rape by a white woman against an African American male was almost tantamount to a death sentence, irrespective of any actual evidence of guilt.
The Scottsboro case, unlike that of Tom Robinson, was recognized as a blatant miscarriage of justice, achieving wide resonance throughout the United States. Another difference is that Tom Robinson was convicted despite having such an outstanding, conscientious lawyer representing him at his trial in the shape of Atticus Finch. However, the Scottsboro Boys, initially at least, were severely hampered by inadequate legal representation, a common occurrence for African Americans at that time.
http://www.encyclopediaofalabama.org/article/h-1456