One explanation could be the climate difference. Egypt has a very hot and dry climate compared to Greece. Egypt would have more than likely focused on getting resources to survive rather than recreational activities such as art as much which explains why they didn't imporove on it dramatically. This idea is also prevelant in the two golden ages of Egypt and Greece. In Egypt the golden age focused on lots of trade with other countries. While in Greece the golden age focused on cultural advancements in the arts and architecture.
