In which way does the story of Richard sets itself apart from the canon? the style and the tone of the narration and how it evolves throughout the book.

I'm not sure which canon you are referring to. I can comment on his style though. Black boy is really fashioned after an autobiography. Instead of a smooth chronological narrative, we are given a choppy stream of conscience type of memoir. Richard is very colloquial, like he was telling his story to you over a bear in a pub. It is full of "one time I remember" and statements like that. THe narrative is really a series of stories linked together that the reader hopefully finds interesting with an intimate sort of tone.