In a parliamentary democracy, the executive branch is led by a Prime Minister who is elected from the legislative branch (parliament). The Prime Minister is accountable to parliament, and can be removed from office by a vote of no confidence. In contrast, a presidential democracy has a separation of powers between the executive (President) and legislative branches. The President is elected separately from the legislature and serves a fixed term, independent of legislative support. The President also has veto power over legislation passed by the legislature. Overall, the key difference lies in the relationship between the executive and legislative branches of government. Parliamentary democracies have a more integrated system where the executive is accountable to the legislature, while presidential democracies have a more separated system with checks and balances between the branches. The specific powers and duties of the executive, as well as the level of separation or integration with the legislature, can vary depending on the country's constitution and political system.