The two types of text tend to use different techniques: consider in particular metaphors and analogies, both of which compare one thing to another. Analogies are used in nonliterary texts to make things clearer; hence my surgery's leaflet described the detached retina as coming away from the wall of the eye in the same way damp wallpaper peels away from a wall. This ties in with one common aim of the nonliterary text which is to inform clearly about an unfamiliar topic, like a school text book. Other nonliterary text seek to entertain like a spy novel, adventure or science fiction novel or romance.