The key differences between a parliamentary system and a presidential system of government include the relationship between the executive and legislative branches. In a parliamentary system, the executive (prime minister) is drawn from the legislature and is accountable to it, facilitating swift policy-making. Conversely, in a presidential system, the president is elected independently of the legislature, resulting in a separation of powers that can lead to gridlock. Accountability mechanisms also differ, as parliamentary systems can be dissolved through votes of no confidence, while presidential systems typically require fixed terms, making political dynamics and governance approaches distinct.