What is the difference between presidential system and parliamentary?

In a presidential system, the president is both the head of state and government, elected separately from the legislature, which allows for a clear separation of powers. In contrast, a parliamentary system combines the executive and legislative branches, with the prime minister being chosen from the legislature and often requiring its confidence to govern. This can lead to a more collaborative relationship between the executive and legislative branches in parliamentary systems, while presidential systems may experience more gridlock due to their separation.