<P> In parliamentary systems the head of state may be merely the nominal chief executive officer, heading the executive branch of the state, and possessing limited executive power . In reality, however, following a process of constitutional evolution, powers are usually only exercised by direction of a cabinet, presided over by a head of government who is answerable to the legislature . This accountability and legitimacy requires that someone be chosen who has a majority support in the legislature (or, at least, not a majority opposition--a subtle but important difference). It also gives the legislature the right to vote down the head of government and their cabinet, forcing it either to resign or seek a parliamentary dissolution . The executive branch is thus said to be responsible (or answerable) to the legislature, with the head of government and cabinet in turn accepting constitutional responsibility for offering constitutional advice to the head of state . </P> <P> In parliamentary constitutional monarchies, the legitimacy of the unelected head of state typically derives from the tacit approval of the people via the elected representatives . Accordingly, at the time of the Glorious Revolution, the English parliament acted of its own authority to name a new king and queen (the joint monarchs Mary II and William III); likewise, Edward VIII's abdication required the approval of each of the six independent realms of which he was monarch . In monarchies with a written constitution, the position of monarch is a creature of the constitution and could quite properly be abolished through a democratic procedure of constitutional amendment, although there are often significant procedural hurdles imposed on such a procedure (as in the Constitution of Spain). </P> <P> In republics with a parliamentary system (such as India, Germany, Austria, Italy and Israel) the head of state is usually titled president and the principal functions of such presidents are mainly ceremonial and symbolic, as opposed to the presidents in a presidential or semi-presidential system . </P> <P> In reality, numerous variants exist to the position of a head of state within a parliamentary system . The older the constitution, the more constitutional leeway tends to exist for a head of state to exercise greater powers over government, as many older parliamentary system constitutions in fact give heads of state powers and functions akin to presidential or semi-presidential systems, in some cases without containing reference to modern democratic principles of accountability to parliament or even to modern governmental offices . Usually, the king had the power of declaring war without previous consent of the parliament . </P>

Identify and explain the one difference between a head of state and a head of government