-The Catholic Church had some innovations as per the living magisterium, for example, it elaborated on the concept of purgatory, the papacy, and mariology. In these areas you find significant differences with the Orthodox, but these are not properly Holy Tradition for the Catholic, but rather magisterial teaching.-
Magisterial teachings are considered infallible teachings?
If so, then the OC is heretical?
Not necessarily; it depends how they are made. Certain fundamental elements of the teaching on Purgatory, Mary and the Papacy are indeed infallible and they prevent unification. However, it does not make the Orthodox heretical, largely because heresy requires acceptance of the teaching followed by its rejection. Our view is that these sticking points are elaborations on the traditional teachings and not in contradiction with them. One who disagrees with the elaboration nevertheless is not in heresy as long as he adheres to the traditional core.