You are right but there is (at least in theory) a MAJOR difference between US Supreme Court and the Cour de Cassation : the Cour de Cassation can not judge a case, it can only break a decision on form, ie if procedure was not correctly executed. Or course, in reality, they pronounce themselves on substance of decision each time they can find some minor details entitling them to hear the case.

And a last note : the European court of Human Rights is higher than the Cour de Cassation. But its scope is limited and this is true for every country in Europe.