Bound by honor is an autobiography, while The Last Testament deals in detail with commission meetings Bill Bonanno attended, description of the history of the Mafia, the structure of a Mafia Family etc. One chapter deals with hitmen, another with initiation into the Mafia, the ritual used and the oaths taken. I´d say that The Last Testament is actually more of a scholar book (but with some holes, especially on the early history). They are both good reads. Two different kind of books, I´d say.