The Eastern Orthodox would disagree with you. They do not recognize the absolute authority of the pope. Matter of fact, they consider Rome the schismatics.
Both claim to be but have significant doctrinal differences, ones that Rome says damn a man if not adhered to.
So which one is the TRUE Catholic church?
The Orthodox are simply wrong. But even if they are right, the Protestants are still wrong. Other than the question of the papacy, Catholics and Orthodox present a common witness to the apostolic faith.