This document discusses the difference between prepositions and adverbs. It provides examples of terms being used as prepositions versus adverbs. A preposition takes an object, such as "out the window", while an adverb does not, like "sat down". Many terms can be both prepositions and adverbs depending on whether they are followed by an object or not. The document also categorizes different types of adverbs like place, manner, time, frequency and duration.