There is no hard-and-fast distinction between the terms figure of speech and poetic device, however, the two terms are not always interchangeable.
The term figure of speech refers to figurative language that is usually colloquial or drawn from common speech. Examples of figures of speech would be:
- Aphorisms – “A bird in hand is better than two in the bush.”
- Sayings/Colloquialisms – “Isn’t that the pot calling the kettle black?”
- Common Metaphors – “He was stuck on that business idea like white on rice.”
The term poetic device has a somewhat broader meaning and can be used to describe almost any intentional use of figurative language, hyperbole, allusion, analogy, or stylistic element that demonstrates an artistic intention on the part of the writer or utilizes a standard poetic convention (common use of language).