Benzema is a different player than Cristiano Ronaldo and their common thing is only their great talent. However Benzema can adapt well to his head coach and teammates as well as is able to sacrifice his favorite position for best benefit of the team. In contrast, Cristiano Ronaldo is more selfish and he cares more about himself, his personal performances, records, and awards than the team perforamances. Generally head coaches are more easily and comfortably in working with Benzema than with Cristiano Ronaldo.
Of the two players you mentioned, Karim Benzema certainly has extraordinary talent, thanks to which he has been able to adapt properly to his head coach Laurent Blanc and show surprises. Even Cristiano Ronaldo is able to adapt very quickly to the team and the coach, which is why he can perform extremely well, if you look at it a little more closely.
Karim Benzema is one of the most successful players in this season of the Saudi Pro League as most people observe that he has won two trophies this season. According to the history of this league, we can say that Al Ittihad has never been able to claim the double trophy, that is they have never won their domestic league title and the King's Cup trophy together in the same year.