I think there was a big difference between Michael and Vito. Michael had more of a temper (Vito would never raise his voice to Tom Hagen) and he was less reluctant to settle things through negotiations. In the scene where Vito makes the deal with the other families so Michael can come home, he makes the point that he has "never" refused an accomodation except on the drug issue. Michael, on the other hand was never interested in accomodating anyone.

No question that everyone feared Mike, but whether they respected him was something else. In GF III even Don Altobello, an old ally devided it was time to take Michale out, and Michael himself in the famous Dontomassino open casket speech asks out loud why was Dontomassino so loved while Michael was so feared even though both of them were equally honorable.
Michael was not loved because he didnt give much. Vito built his empire on doing favors for other people and then getting favors in return. Michael did it more form the barrel of a gun.