Final answer:
Ur is distinguished from earlier periods by becoming the capital of an empire, with the Ziggurat of Ur as a major religious and political center, and showcasing advanced craftsmanship and arts.
Step-by-step explanation:
A distinctive feature of Ur compared to earlier Sumerian cities such as Eridu and Uruk is its development from a city-state to the capital of an empire. The archaeological findings at Ur, notably from the excavation led by Leonard Woolley, uncovered a highly developed urban center with advanced religious architecture, like the well-preserved Ziggurat of Ur dedicated to the moon god Nanna.
Dating to the period between 2100 and 1800 BCE, the ziggurat signifies not only the architectural evolution but also the religious and political significance of the city-state as it became the capital of an empire. Additionally, this period is marked by beautiful arts and crafts, exemplified by items such as the intricate wooden box found in a royal tomb, showcasing the city's prosperity and the craftsmanship skills enabled by its stable agricultural base.