I think the difference between Vito Corleone and Michael Corleone was that Vito was the beginning of the family and her mafia to protect the family, so all the family members were nice to her and did everything for his of course, it was reciprocal.

But Michael and even Sonny was in fact the heir apparent of the Mafia, and not only was he unable to gain the support of the family, and not only was he unpopular with family members, but he even found mafia connections within the family, and they were betrayed.