How is a parliamentary democracy different from a presidential democracy in terms of the structure and functioning of the government?

In a parliamentary democracy, the executive branch is led by a prime minister who is chosen from the legislative branch, while in a presidential democracy, the executive branch is separate from the legislative branch and the president is elected independently. This difference affects how the government is structured and how it functions, with parliamentary democracies often having a more fluid relationship between the executive and legislative branches compared to presidential democracies.