These letters accomplish two different objectives two different ways, which I think is really essential to recognize.
Malcom X writes to inspire others. His story is short and sweet and communicates one very important message: I have done it, and so can you. It is about waking up and reading all there is to read in order to gain a bountiful amount of knowledge. Knowledge is freedom.
MLK on the other hand calls people to action. His letter reminds me of a sermon. It takes me on a journey through reason and answers the questions that I have. It gives me a different perspective on something that I haven’t been looking at, and then calls me to go and stand up–not directly, of course, but instead gives me no other moral option.
Composing Self - J. Carpenter 