Compare and Contrast the style of the Late Antique (Roman) with Byzantine Art

The art of the "Late Antique" or Early Christian period in Rome is stylistically different from the art produced in the eastern Roman, or Byzantine empire. Compare and contrast either the mosaic depicting "Christ as the Good Shepherd" from the Mausoleum of Galla Placidia in Ravenna with the mosaics from San Vitale in Ravenna or two images of your liking. What are the differences and similarities between the two images? Some areas you may wish to discuss are the depiction of space and representation of the natural world. Is the Roman concern with realism evident in Byzantine art? Why is Byzantine art so strikingly different from the art produced in Rome? Were mosiacs used differently in the Byzantine church compared to their use in Rome?