Maybe it was just a matter of traditions changing, but notice how in GFI that nobody refers to Vito by his first name; nobody calls him less than Don Corleone or Godfather, not even his contemporaries in the other Families. Whereas in Part II, plenty of people--Frankie, Roth, etc--all at different points call Michael by his given name and not by Don Corleone. Is it that he was less respected, or had traditions simply changed?
