The Art of English

What is the difference between idioms, proverbs, metaphors and quotations?

Idiom: group of words in a fixed order forming an expression whose meaning is not predictable from the usual meanings of its constituent elements/words.

Proverb: a short sentence, etc., usually known by many people, stating something commonly experienced or giving advice or a short popular saying, usually of ancient origin, that expresses effectively some commonplace truth or useful thought.

Metaphors:  comparing one thing to another thing used refer to something that it does not literally denote in order to suggest a similarity.

Quotations: a well-known and wise statement made by famous people, which often has a meaning that is different from the simple meanings of the words it contains.