What are some similarities in the achievements of Frederick Douglass and Malcolm X?

Two similarities in the achievements of Frederick Douglass and Malcolm X lie in the way they taught themselves to be literate and in the tone of their writings.
Both men did not receive strong and sustained formal instruction in literacy. As a slave, Frederick Douglass did not even receive an education.  He initially learned the fundamentals of reading from Sophia Auld, one of his mistresses. Upon hearing of what his wife was doing, Hugh Auld forbade her from teaching the slave.  Douglass had to piece together the elements of literacy instruction from outside sources.  His reading and writing skills were self-taught.  Malcolm X's path followed a similar arc. While he did receive formal education, it was limited.  Malcolm X dropped out of school and lacked a foundation for effective reading and writing.  While he was in prison, he relearned the skills needed to be an effective reader and thinker. This took the form of familiarizing himself with every word in the dictionary and reading increasingly complex works. Like Douglass, his building of reading and writing skills took place under his own guidance. 
Both men are also similar in the defiant tone they strike towards white society. Frederick Douglass is unabashed in his condemnation of slavery.  He does not believe that slavery needs to be gradually eliminated.  He demands its dissolution.  He sees it as "fatal poison." When he challenges Covey, Douglass shows a defiance associated with his stance on slavery:  "You have seen how a man was made a slave; you shall see how a slave was made a man.’’ Malcolm X was equally forceful in his opposition to racism perpetrated by members of the white community.  This blunt rejection of racism is seen in his insistence that African-Americans must achieve their freedom "by any means necessary" and in his advocation for self-defense.  Like Douglass, he was unapologetic about his approach.  Both men are similar in how the tone of their work caused consternation in the white community. Both men's legacies were forged because of this tone towards injustice.