The differences are no really very big. Both Civilizations grew on the banks of rivers,in Egypt the Nile and in Mesopotamia the Tigris and Euphrates. They would not have existed if it was not for these rivers. Egypt is mainly desert with a few Oasis in the Eastern Desert and the fertile Nile Delta in the North,which is very similar to the part of Mesopotamia where the two rivers come closest to each other. Mesopotamia has a mountainous region in the North which borders with today's Turkey (Kurdistan)and a great part between the two rivers is swamp which has been drained since ancient times,the rest of the country is very dry and in some parts desert.
These two Civilizations could grow because the rivers gave them unlimited access to drinking water,made transport much more easy and the land near the rivers was so fertile they could get as much as three crops a year. The climate in both countries is mild to hot which makes living conditions easier. All in all the lives of the people was quite easy and allowed for free time which could be used for making their lives better by inventing and adorning their creations. Thus these two great Civilizations were born. Gifts of the Rivers they quite rightly adored as Gods.