In a monarchy an emperor and king are both rulers, but the power associated with them is different. They can be compared to regional manager and the CEO of a company. An empire can have many kingdoms within it; the emperor rules the entire empire while kings (or queens) rule smaller kingdoms within the empire. While the king (like the regional manager) has total control over his territory, the emperor (like the CEO) is the one who makes the final decision for the entire region.

This distinction is not universal. There are many examples in history where large kingdoms have been called empires but have been ruled by a single monarch, a king or queen. For example, King George V, Edward VIII and George VI were all kings of the United Kingdom and emperors of India.

Comparison chart

Emperor versus King comparison chart
Edit this comparison chartEmperorKing
Female ruler Empress is the female form, who can be the wife or mother of the emperor, or the ruler of the empire. The female form is known as Queen. She can be the wife or mother of the King, or ruler of the Kingdom.
Source of power Inheritance or by conquest Inheritance, by conquest or elected
Modern rulers Today the Emperor of Japan is the only remaining emperor on the throne in the world. The King of Spain is an example.
About An Emperor is the ruler of an empire. An emperor is a (male) monarch, usually the sovereign ruler of an empire or another type of imperial realm A king rules a kingdom, might be a part of an empire.
Divine status Emperors may be considered a God within their Empire (as with the Emperor of China), or their divine status may be appointed by the Grace of God, (as with the Holy Roman Emperor) Like Emperors, Kings may be considered Gods within their own Kingdom, alternatively they may reign by the Grace of God.
Power The power of emperor is maximum, the whole empire is under his command. Most have lesser Kings as vassels, sworn to them. Historically the power of many Emperors was often less than that of contemporary Kings. For some power of Kings maximum in his kingdom, for others they may be vassels to a greater monarch. Some Kings, such as those in France and Britian ruled over far greater terretories than most Emperors.
Politics Many kingdoms with their different policies and politics form an empire, and the ruler i.e. the emperor is the ultimate ruler of all the kingdoms. Each kingdom has its boundary and it’s own politics and a king is the ruler that kingdom. Often a King will rule over several Kingdoms in a personal union, some such as the Kings of Great Britain also held the substitutiary title of Emperor of Indi

What is a Kingdom?

A kingdom is a state or province, which may be independent or a part of a bigger empire.

Empire and emperor

When a king conquered his neighboring kingdoms and united them all under his command, he became the emperor of his entire region, which was now called an empire. So an Emperor has control over a vast area and King’s power is limited.


An emperor had the highest power in the whole empire. He represented the empire as a whole which was further divided into further kingdoms. Most kings were engaged in battle during those times to expand their kingdom. Kings usually represented a larger system which had  and customs regarding succession, duties, and powers. The Emperor was the one who incorporated the rules and policies of the empire. The king within the empire helped in implementing these rules.

Source of power

Traditionally, hereditary succession within members of one family has been the most common mode of electing a King while an emperor can be elected either by inheritance within the family or by defeating a King.


Today most of the kingdoms have been abolished, only a few like England still remain. The only ruling emperor includes the emperor of Japan.

Female ruler

A female ruler of a Kingdom is called a Queen while a female ruler of an Empire is called an Empress.


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"Emperor vs King." Diffen LLC, n.d. Web. 18 May 2022. < >