How good with ancient Christian history are you? All issues with Oriental vs. Eastern Orthodox have to do with a 5th Century council in Chalcedon.
I recommend you start with first learning what the faith is in each church. Then, you may proceed to learn about the intricacies and history of this faith.
Oriental Orthodox Church includes Coptic, Syriac, Armenian, Ethiopian, Eritrean, Malankara Orthodox Syriac, Malankara Syriac Orthodox, British Orthodox
Eastern Orthodox Church includes Ecumenical Patriarchate, Alexandrian Greek, Antiochian Greek, Greek Orthodox, Russian Orthodox, Jerusalem Patriarchate, Ukrainian, Serbian, Carpatho-Russyn, OCA, etc.