The Sumerians were the first people to migrate to Mesopotamia, they created a great civilization. Beginning around 5,500 years ago, the Sumerians built cities along the rivers in Lower Mesopotamia, specialized, cooperated, and made many advances in technology. The wheel, plow, and writing (a system which we call cuneiform) are examples of their achievements.
1 In a presidential system, the legislature and the executive do not have to be aligned and often work against each other. 2  Policy implementation can be much slower and more moderated, at least in the US system.
Parliamentary: Prime Minister not directly elected and he is not the Head of State. Presidentialist: President is Chief Executive, Head of State, AND Head of Government. Parliamentary: No Separation of Powers. Presidentialist: Seperation of Powers between the different branches of the government. Parliamentary: Prime Minister must have the confidence of the parliament. With a vote of no confidence he is removed. The Prime Minister can dissolve Parliament. Presidentialist: Impeachment is the only legal way to remove the President from office.