Is there a difference between the Sicilian mafia and the italian mafia?

Because i always hear in mafia films how the sicilians are crazy and these are normal mafia guys saying this. But in a lot of films all of them were born in sicily, so i don't get it. Do you have to be sicilian to join the mafia or can you be from any part of italy. Also if they are two separate things, whats the difference between the two mafia's?