How did the organization of Medieval European societies differ from that of Rome at its height?

With the fall of Rome, an empire came to an end. In other words, all the benefits of an empire were over. This would include, good functioning communication, broad infrastructure, such as roads, a centralized taxation system and even safety to some extent. What came to pass instead was a number of groups, such as the Franks, Goths, etc. These were independent groups that often fought each other. Eventually all of this lead to feudalism and more independent kingdoms.