What are the main differences between Eastern Orthodoxy & Oriental Orthodoxy ?
Doctrinally? (Almost) nothing.
What separates them ?
"The Oriental Orthodox churches came to a parting of the ways with the remainder of Christianity in the 5th century. The separation resulted in part from the Oriental Orthodox churches' refusal to accept the Christological dogmas promulgated by the Council of Chalcedon
, which held that Jesus Christ is in two natures — one divine and one human, although these were inseparable. To the hierarchs who would lead the Oriental Orthodox, this was tantamount to accepting Nestorianism. In response, they advocated a formula that stressed unity of the Incarnation over all other considerations, that being "one nature of God the Word Incarnate", "of/from two natures" in and after the union. The Oriental Orthodox churches are therefore often called "Monophysite" churches, although they reject this label, which is associated with Eutychian Monophysitism, preferring the term non-Chalcedonian or Miaphysite churches. Oriental Orthodox Christians anathematize the Monophysite teachings of Eutyches. They are sometimes also known as anti-Chalcedonians.
In the 20th century, a number of dialogues have occurred between the Oriental Orthodox and the Chalcedonian Orthodox which suggest that both communions now share a common Christology with differing terminology. As yet, full communion has not been restored."
And also the recognition of different Saints.