What is the difference between Idiom and Expression?

Idiom and Expression are two different things, but some people still treat the two as though they are one. Idiom and expression are two different ways of communicating our intentions to people through the use of words. An idiom is simply a manner of speaking, or a way of expressing oneself through the use of words or phrases that seem illogical and most times, cannot be easily understood, because it might take you a very long time for you to figure out its actual meaning. People use idiom to engage with themselves at a higher level of communication. Example of idiom is 'to put round pegs in round holes'.

An expression, on the other hand, is also a manner of speaking, or a way of expressing oneself through the use of direct words that can be easily understood. This means, the difference between idiom and expression is the simplicity of the words being used and the arrangement of those words or phrases.