The biggest differences are summed up:
“In any case, Orthodoxy has always put great stress on “mastery of the passions” through prayer (public worship and private devotions), fasting (self-denial) and voluntary obedience and regular participation in the Eucharist (sometimes called “the Mysteries”). Thus, the highest form of Christian living (”the supreme philosophy”) is monasticism. Here all human energy is devoted to struggle for perfection.
Monasticism, in this sense, among Roman Catholics has all but disappeared. As a “supernatural religion” so-called, it has become increasingly “this-worldly.” Therefore, it has abandoned its medieval heritage, and its understanding of man, his nature and destiny has become increasingly secular. “
This characterization of monasticism among Roman Catholics is exaggerated, but it does illustrate the point. Monasteries, while less emphasized in the West, still exist in some numbers. In our current state, we have emphasized different aspect of the doctrine, that’s all.
The OC teaches that when Adam sinned against God, he (Adam) introduced death (not sin) into the world. All men inherit death; the Atonement was not necessary to atone for "original sin," because there is no "original sin" to the OC.
The doctrine of original sin is the difference not monasticism. Do you not see that? or are you being disingenuous?