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Emperor Vs King: What's the Difference?

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Throughout history, rulers have acted as living embodiments of might, power, and even divinity. These monarchs hold supreme authority. Their actions and decisions can shape the destinies of their people for centuries to come. Many names are bestowed upon these rulers - they are most frequently called kings and emperors.

How is a king different from an emperor?

The most apparent difference between the two titles relates to the size of their domains. Empires are usually understood to be much larger than kingdoms. Likewise, emperors are sometimes seen as more powerful than kings. 

Read on to discover how else kings can differ from emperors.

What is a King?

Louis XIV, King of France
Louis XIV, King of France

We can view kingship as the highest position of power that a male ruler can occupy in a kingdom. 

As monarchs, they are able to rule until they die or choose to abdicate. The line of succession within the royal family determines who will inherit the title of kingship. 

The extent of a king’s responsibilities, powers and influence over other estates or bodies of government can vary considerably. They may rule with absolute power, or they can be checked and limited by a constitution. 

The king is conventionally seen as the head of state. A Prime Minister may take the reins as head of government.

What is an Emperor?

Napoleon, Emperor of the French
Napoleon, Emperor of the French

Emperors are male rulers who occupy the highest seat of power in an empire. 

An emperor largely has the same powers and authorities as a king, as well as a similar system of succession and status as a monarch, although the word carries a much more prestigious connotation.

If we consider historical examples of empires – such as Ancient Rome, the Byzantine Empire, the Russian Empire, and the British Empire – one will find that these states are composed of vast tracts of territory.

Consequently, emperors often rule over several lesser kingdoms within their realm, and therefore hold more power than kings in client states. 

Differences Between a King and an Emperor 

Territorial Policy

A key aspect that distinguishes emperors from kings lies in the territorial ambitions of their states. 

An emperor is often interested in expanding the territory of his realm through conquest, colonization and alliances. By gaining new territory, emperors can get access to more land, resources, subjects and wealth to further strengthen their state. 

While it is not a definite rule, kings are mainly interested in preserving the current size and stability of their kingdom. They may also attempt to expand their domains or resolve border disputes, but they are not as fixated on imperialistic aims as emperors.


As a consequence of their expansionist ideals, most great empires throughout history control huge swathes of territory – the Mongol Empire, for instance, virtually dominated mainland Asia, while the British Empire built colonies all over the world.

Kingdoms may differ substantially in size. Some, like monarchic France, Korea, Poland or Sweden, held a decent amount of land and were able to become regional or great powers. Others, like Liechtenstein, are much smaller. 

Roles and Responsibilities

Both titles are traditionally monarchic. Many kings and emperors were despotic or autocratic – ruling with total authority. They could decree laws into existence, judge and punish criminals, and declare war.

Constitutional monarchies – in which the sovereign’s powers are limited and exercised by the electorate – are more common among kings and queens

Kings and emperors were often sovereigns for life, and thus could drastically alter the level of prosperity and power found in their state. 

In broad terms, emperors could quantitatively hold more power and responsibilities than kings due to the larger scale of their economy, military, and influence.


Traditionally, a king in a European or Western kingdom is addressed as “His Majesty.” Throughout Korea’s history, sovereigns have been known as Wang (King) or Daewang (Greatest King).

Likewise, in Europe, an emperor is styled as “His Imperial Majesty” or variations thereof. In Japan, the emperor of the Chrysanthemum Throne is entitled “Tennō” – meaning “heavenly sovereign.”


The Modern English word “king” is Germanic in origin, initially meaning the “scion of a [noble/royal] kin” to refer to the rulers over tribal kingdoms. It later developed as “cyng” or “cyning” in Old English before transforming into its current incarnation.

In contrast, the word “emperor” traces its roots to Latin, beginning with the word used to describe Augustus Caesar as hegemon of Ancient Rome – “imperator”, which meant “commander.” It survived as “emperere” in Old French before developing into its current form.

The name “Caesar” itself has also become synonymous with “emperor” in many languages, including German (Kaiser), Russian (Tsar), and Turkish (Kayser).

Comparison Chart: King Vs Emperor 

Territorial PolicyVaries – generally less fixated on increasing territoryUsually expansionist – interested in gaining land
RealmCan occupy a large region of a continent, or be much smallerOften spanning across one or more continents. May have several colonies
Roles and ResponsibilitiesCan wield absolute power or be constitutionally limitedSimilar to kings, although the size of their domain may demand more attention
Style“His Majesty”“His Imperial Majesty”
EtymologyGermanic originLatin origin

How are Kings and Emperors similar? 

As monarchs, kings and emperors – by definition – can have a substantial degree of overlap in several aspects.

Both rulers are destined to rule for life. When they reach old age, they may abdicate the throne to let an heir succeed their throne. The line of succession usually determines which heir will be crowned as the next sovereign.

Whether their reign is absolute or constitutionally-limited, kings and emperors hold a superlative degree of power over their subjects. 

Many kings can be titled as ‘emperors’ in the course of their lives. An emperor may also be called a “king of kings.”


Why was the Russian Empire so big?

The present-day country of Russia can easily be found on a world map due to its enormous land territory, largely thanks to the expansionist ambitions of Tsar Ivan the Terrible during the 16th century

Ivan spurred the Russians to conquer and colonize Siberia, which was composed of the land east of the perilous Ural Mountains. It integrated the local tribes there with little difficulty due to their interest in trading. 

By 1645 – just the span of a century – the borders of the Russian Empire reached the Pacific Ocean.

What was the first known kingdom?

Sumer currently holds the record as the oldest known kingdom. It was established around the 4th millennium BCE in Mesopotamia (now the southern part of Iraq), although evidence suggests it was settled as early as the 5th millennium BCE.

Gilgamesh, the Sumerian king of Uruk, is the most famous king of Sumer, in part due to his eponymous epic, and his numerous depictions in later fiction – including the popular Fate series of video games. 


Unlike the common folk, kings and emperors can wield an immense degree of power in their respective states and abroad. 

These male sovereigns usually rule for the rest of their lives, inheriting their titles through a line of succession, and may use their ideally long reign to further the interests of the Crown and the people. 

While they are largely similar, emperors often reign over larger territories and nurture expansionist ambitions, and even lord over other kings whose states are part of their empires.

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About the Author: Nicolas Seignette

Nicolas Seignette, who holds a scientific baccalaureate, began his studies in mathematics and computer science applied to human and social sciences (MIASHS). He then continued his university studies with a DEUST WMI (Webmaster and Internet professions) at the University of Limoges before finishing his course with a professional license specialized in the IT professions. On 10Differences, he is in charge of the research and the writing of the articles concerning technology, sciences and mathematics.
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