Arp, I've mostly only done Catholic/Lutheran/Calvinist differences, so probably not very easily. The key thing is that they don't have any of the "infallible pope" stuff, I guess; their leader, the Patriarch of Constantinople, is seen more as a "first among equals". There used to be 5 patriarchs (Rome, Alexandria, Constantinople, Antioch, Jerusalem) but all bar Rome and Constantinople disappeared in the first wave of Islamic invasions, and the remaining two then split. They're very into icons of saints, different dress code, and their churches look very different (the Western church building is based on the Roman basilica, the Eastern is a more square, domed building).