Difference between metaphors and idiomatic expressions

Defections from one side of the political divide to another have been witnessed in recent times. Some individuals have switched sides, purporting to move over with large sections of an electorate that rejected them on August 8, 2017.

It is in the human nature to seek justification for our actions, especially where conscience troubles one over the right or wrong of them. What the larger public knows, however, is the `carrot and stick’ approach that any political party in power, and seeking to entrench that power, would employ. The expression ‘carrot and stick’ is alternately an idiomatic expression and a metaphor. ‘Alternately’ is sometimes confused with ‘alternatively’, but they have different meanings. To alternate is to take turns at doing something.  ‘Alternative’ is an ‘option’, sometimes used in place of ‘otherwise’.