Prose - I like it in novels because it's the main content
Fluff, polish, whatever - Not the main content, but making the main content better? Supporting it?
What's polish? It's what's not needed.. Make sure you communicate everything you need to communicate (main content); then add stuff after that which stands on its own! Prose and descriptions and lore, for example, can be added and nothing relies on them, so this frees them up -- frees the polish up -- to be good for its own sake.