Sweden, or the United Kingdoms of Sweden and Norway, is a constitutional monarchy.
Sweden is unusual in that it has two separate parliaments connected by one monarch. However, both the Swedish and Norwegian parliaments have different powers.
The Norwegian parliament consists of 190 members elected every four years by universal adult suffrage, the leader of the party who holds a majority in the parliament, or in case of a hung parliament the member of parliament who has the support of the most MP's, is appointed chairman of the council and given responsibility for forming a government and managing domestic affairs.
The Swedish parliament consists of 310 members elected every four years by universal adult suffrage, the leader of the party who holds a majority in the parliament, or leader of the largest party, is appointed prime minister. The prime minister acts as the head of government of Sweden, but is given responsibility for forming a cabinet that wholly represents the Union. Consequently all cabinets since the current constitution was formed in 1920 have the obligation to include Norwegian MP's in them. Usually, one of the three great posts (Foreign Minister, Interior Minister or Finance Minister) is occupied by a Norwegian.
The King, on the advice of his Prime Minister, appoints a 15 person royal council, consisting of unelected bureaucrats or former MP's. The council works closely with the King, keeping him personally informed and effectively acting as his own personal cabinet.