What is the difference between Head of State and Head of Government?

Answer 1

In a parliamentary system such as a constitutional monarchy or a parliamentary republic, the Head of State has a ceremonial role and does things like give out medals, open parliament and is the official head of the military. The head of government deals with making policy and leads the government.
This question pertains primarily to nation-states with a parliamentary type of government. That is to say, the people elect their representatives in a national assembly, or parliament, and then a majority of the members of the assembly elect the prime minister to form a cabinet of ministers and run the government. Thus, the primer minister is the "head of government", while there is another person who is the "head of state" This "head of state" is the representative of the entire country, who represents that country abroad or within the country at ceremonial occasions, or who may have the power to receive ambassadors from other nations, or to affix his/her signature to a treaty or a declaration of war.

It is also important to note here that amongst the nations of the British Commonwealth, especially those who have a Governor General and a Prime Minister, that the Governor General, who represents Her Majesty Queen Elizabeth II of the United Kingdom of Great Britain and Northern Ireland, is the Head of State (Canada, Australia, New Zealand, and a few others), and the Prime Minister, again, is the Head of Government. However, although the Governor General supposedly represents the Queen, in reality the Governor General is nominated by the Prime Minister and is automatically approved by the Queen.