What are the key differences between presidential and parliamentary governments, and how do these differences impact the functioning of each system?

Presidential governments have a separation of powers between the executive and legislative branches, with the president serving as the head of state and government. In contrast, parliamentary governments have a fusion of powers, with the executive branch being drawn from the legislative branch. This impacts the functioning of each system as presidential governments can lead to more checks and balances, while parliamentary governments can result in more efficient decision-making and accountability.