Main Difference
The main difference between King and Prince is that the King is a class of male monarch and Prince is a title of nobility
King
King is the title given to a male monarch in a variety of contexts. The female equivalent is queen regnant in (while the title of queen on its own usually refers to the consort of a king).
In the context of prehistory, antiquity and contemporary indigenous peoples, the title may refer to tribal kingship. Germanic kingship is cognate with Indo-European traditions of tribal rulership (c.f. Indic rājan, Gothic reiks, and Old Irish rí, etc.)
In the context of classical antiquity, king may translate Latin rex or either Greek archon or basileus.
In classical European feudalism, the title of king as the ruler of a kingdom is understood as the highest rank in the feudal order, potentially subject, at least nominally, only to an emperor (harking back to the client kings of the Roman Empire).
In a modern context, the title may refer to the ruler of one of a number of modern monarchies (either absolute or constitutional). The title of king is used alongside other titles for monarchs: in the West, prince, emperor, archduke, duke or grand duke, and in the Middle East, sultan or emir; etc.
King may also refer to a king consort, a title that is sometimes given to the husband of a ruling queen, however the title prince consort is sometimes granted instead.
Prince
A prince is a male ruler ranked below a king and above a duke or member of a monarch’s or former monarch’s family. Prince is also a title of nobility, often hereditary, in some European states. The feminine equivalent is a princess. The English word derives, via the French word prince, from the Latin noun princeps, from primus (first) + capio (to seize), meaning “the chief, most distinguished, ruler, prince”.
King (noun)
A male monarch; a man who heads a monarchy. If it’s an absolute monarchy, then he is the supreme ruler of his nation.
“Henry VIII was the king of England from 1509 to 1547.”
King (noun)
A powerful or majorly influential person.
King (noun)
Something that has a preeminent position.
“In times of financial panic, cash is king.”
King (noun)
A component of certain games.
King (noun)
The principal chess piece, that players seek to threaten with unavoidable capture to result in a victory by checkmate. It is often the tallest piece, with a symbolic crown with a cross at the top.
King (noun)
A playing card with the letter “K” and the image of a king on it, the thirteenth card in a given suit.
King (noun)
A king skin.
“Oi mate, have you got kings?”
King (noun)
A male dragonfly; a drake.
King (noun)
A king-sized bed.
King (verb)
To crown king, to make (a person) king.
King (verb)
To rule over as king.
King (verb)
To perform the duties of a king.
King (verb)
To assume or pretend preeminence (over); to lord it over.
King (verb)
To promote a piece of draughts/checkers that has traversed the board to the opposite side, that piece subsequently being permitted to move backwards as well as forwards.
King (verb)
To dress and perform as a drag king.
Prince (noun)
A (male) ruler, a sovereign; a king, monarch. from 13th c.
Prince (noun)
A female monarch.
Prince (noun)
Someone who is preeminent in their field; a great person. from 13th c.
“He is a prince among men.”
Prince (noun)
The (male) ruler or head of a principality. from 14th c.
Prince (noun)
A male member of a royal family other than the ruler; especially (in the United Kingdom) the son or grandson of the monarch. from 14th c.
Prince (noun)
A non-royal high title of nobility, especially in France and the Holy Roman Empire.
“Prince Louis de Broglie won the 1929 Nobel Prize in Physics.”
Prince (noun)
The mushroom Agaricus augustus.
Prince (noun)
A type of court card used in tarot cards, the equivalent of the jack.