What is the main difference between a presidential system and a parliamentary system of government?

The main difference between a presidential system and a parliamentary system of government lies in the structure of the executive branch and the relationship between the executive and legislative branches.

In a presidential system, the head of state and head of government are separate and the president is elected by the people and serves a fixed term. The president has significant powers, such as the ability to veto legislation and make executive decisions, and is not accountable to the legislature. The executive and legislative branches are independent of each other and co-equal.

In a parliamentary system, the head of state and head of government are typically the same person, known as the prime minister, who is appointed by the legislature. The prime minister is accountable to the legislature and can be removed from office through a vote of no confidence. The executive branch is fused with the legislative branch and the prime minister needs the support of the legislature to govern effectively.

Overall, the key distinction between the two systems is the relationship and balance of power between the executive and legislative branches of government.