Please forgive me if I state something that is incorrect, since I am by no means an expert on the subject. The issue of Chalcedon is extremely difficult to understand since we are dealing with obtuse technical terminology and there was also the issue of politics (which I personally believe lie at the root of the whole problem).
As far as I can determine, the EO and the OO have the same understanding of Christ; they simply were expressing that understanding in different terms.
To believe that Christ was a man infused, so to speak with the Divine, would be Adoptionism, a heresy.
To believe that Christ was a Divine being with external human attributes would be a form of docetism, also a heresy.
Nestorianism, as commonly understood, makes it appear that Christ was two separate persons existing side-by side in one body, another heresy.
The Orthodox position is that Christ is truly human, and truly divine, with these natures neither separated, nor confused. This is believed by both the EO and the OO. The EO say that Christ has both Divine and Human natures, (diophysite) united in one person, neither separated or confused; the OO say that Christ has one nature (miaphysite) that is both completely human and Divine, with the divinity and the humanity being neither separated, nor confused.
This is my understanding, please correct me if I am mistaken. In either case we both see Christ as divine and human, truly Man, and truly God, in one person.
For me it is a matter of semantics. I have also not found any other area in which the EO and the OO differ fundamentally in their theological beliefs and liturgical practices. There are differences with the Roman Catholic Church too numerous to mention, but our beliefs and practices (EO & OO) are identical, other than the Chalcedon conflict. I have no problem considering my OO brothers and sisters to be fully Orthodox Christians. I pray to God that reunion will happen during my lifetime.
In Christ, His unworthy servant,