A territory ruled by a King or Queen is called a Kingdom, whereas a state run by the people through their elected representatives is called a Republic. Europe is a mix of both systems. With a great history of kingdom rulings, some of the countries in Europe in today’s age are run under a republican system of governments.

With the changing eras, the Kingdoms have also changed in Europe. Most kingdoms existing today in Europe are constitutional monarchies. A constitutional monarchy is a modern type of kingdom where the monarch has very less or zero power over the political authorities. The monarch is only treated as a ceremonial head with an inherited identity.
 
All the government affairs are handled by the President or Prime minister, who is given the charge through public voting. The seven constitutional monarchies of Europe include the United Kingdom, Sweden, Spain, Norway, Denmark, Belgium, and the Netherlands.
These modern age kingdoms of Western Europe are good for predetermined continuity and consistency in governments. But a constitutional monarchy has its adverse effects on the people and the ruling authorities of the country.
 

In a republican system of government, the nation is solely governed by the officials who are elected by the nationals themselves. A republic is free from any kind of political influence of a King, Queen, or Emperor. A republic can be federal like Germany or Austria, or it can be a centralized republic like Greece, Hungary, Italy, Romania, Slovakia, and many others.