Both mafia and maffia are used on Sicily. In Italian it is mafia with one f. But in certain Sicilian dialects it is maffia. In English the pronounciation stays the same but in some Sicilian and Napolitan dialects there is a small difference.
But mafia is the common term international, only in Dutch it is maffia.

As for the knowledge of the Sicilian mafia I think that also for Europeans and even Italians it's just more difficult to obtain accurate information about Sicily. Few of the documents and books (if they are even reliable) are translated.
But when you look at little deeper it is true that the Sicilian mafia is more fascinating (also because less is known about it).
I am sure Enzo agrees on this!