Question

why was the eastern empire different from the western empire ?

Answer 1

The Roman Empire divided around two cultural spheres based on different language. While western part embraced Latin language, eastern part was Greek speaking. These two different languages alone had profound effect on development of two separate entities, where culture, social structure, religion, and political order differed significantly between these two.
Western Roman Empire was totally absorbed by barbarians who created numerous independent kingdoms on its ruins. The Eastern Roman Empire, Byzantine, was not absorbed after the collapse of the antique world, and continued until Ottoman conquest. The city of Rome did not control anymore of its former territories, while Constantinople became megapolis of the large empire, and leading center of world’s civilization. The spoken Latin language became extinct and replaced either by descendants of it or supplanted by Germanic language. Greek language survived until today.
Christian religion played crucial role in halving the Roman Empire, where Greeks pursued distinctive rites, and draw on Christian philosophy that was considered heretical for many Latin speaking Christians. Western Christianity became influenced by St. Augustine writings, while Eastern by John Chrysostom, and Basil. The split between these two churches grew overtime, and was completed by 1054 with mutual excommunication.
Politically was Byzantine Empire consolidated into the hand of emperor, who had significant power. Kingdoms arising on the ruins of the western part, had often ruling class of warriors, who co-shared power with the king. This helped Roman church to easily consolidate its power and emerged as the balancing element of that time. Economically, Western Europe was in deep ruin, plundered, impoverished, and brutalized by the collapse of the central authority. Entire region went into total demise. Byzantine Empire prospered, kept its bureaucracy intact, and tax based undisturbed by barbarians rides.