Any profession has a specific set of skills and tools to help workers in that field do a good job, and for writers, those skills include narrative elements and literary devices. Narrative elements are terms of storytelling while literary devices are the tools of language used in storytelling.
Narrative elements include setting, plot, characterization and conflict. All of these elements combine in a way that allows the author to tell a compelling story. As an author develops his or her craft, these elements become leaner and flow together to create a seamless story. New authors sometimes find their work disjointed, and that is because one or more of their elements are working against each other rather than together. Literary devices include alliteration, metaphors, similes, irony and parallel structure. These are the tools that help authors convey meaning within the story. They're also useful for presenting the story's theme without stating it directly.