Many of the discontinuities evolved gradually as the east separated from the west, rather than being sharp ruptures. Some of the major changes were:
The Greek east, ruled from Constantinople, spoke Greek and the Latin west, ruled from Rome, spoke Latin.
Although the Eastern Schism did not occur until much later, the eastern church and the Roman church had differences, leading to e.g. the earlier Photian schism, over such issues as tonsures, leavened vs. unleavened bread in the Eucharist, the filioque (6th century on), Illyricum, icons, and whether the Bishop of Rome was a member of the Pentarchy or had the right to dictate to all of Christendom under the title of “Pope”.