Let us first differentiate between these two categories:
- A figure of speech is a specific term and it uses words or language that goes beyond its literal interpretation, like simile, metaphor, hyperbole.
- A literary device is a linguistic or literary technique that creates a specific effect. It is more general term, which includes a figure of speech, plot mechanism and narrative style, etc.
So, according to above mentioned description, satire fits very well in the first category, a figure of speech.