Both Egypt and Mesopotamia based their social culture through religion, but the Mesopotamians believed that the gods punished them for their wrong doings and thats why the river flooded unpredictably giving them a pessimistic view of the gods and eternal life. The people of Egypt didnt fear the gods because the world was always good to them by the river always flooding at the same time of year helping the soil be good for their agriculture which gave them a more cheerful and hopeful outlook of the world and the gods they worshiped.
The main difference between the two valleys socially were that in Egypt it was more of a positive and well being environment, while in Mesopotamia the atmosphere was very unequal between genders and they were never happy because the gods were never happy with them. Egypt and Mesopotamia had different ways of politics since Mesopotamia was a democracy it had a king who claimed to be patron deity and who controlled the affairs of the walled city and surrounding rural area.
In Egypt they had a centralized government which means the pharaoh was treated like a king, but everyone below him was fairly equal (even the women, though they were still slightly below the men). The main difference between the two valleys politically is that Mesopotamia had a king that made the rules and was the one in charge of everything while in Egypt the Pharaoh was like a king except the people below him had a voice and were treated more equally.
Religion is very similar in Mesopotamia and Egypt by both being polytheistic and the fact that the king/Pharaoh was supposively the closest to god in the valley, the king/Pharaoh would have many sacrifices when something bad happened. They also had animism and used carvings, drawings, and statues to show their beliefs towards the gods. And though their gods were not the same the views of the afterlife and beliefs were very similar.
The main similarities between the two valleys religion was theyre both polytheistic and that their beliefs were very similar towards the gods and the afterlife. In conclusion the two main differences were social and political views when it came to gender equality, classes (rank), and the way the gods treated the people. The main similarity was religion in the way they showed their beliefs in gods and what would happen when they do wrong things and when they die.