The major difference between a preposition and adverb is that a preposition describes the relationship between two things, while an adverb describes or modifies an action. Prepositions include words like “on” and “around” that help describe how two objects or ideas are related in terms of time or position. Adverbs, on the other hand, are used to describe a single word or object; they typically modify verbs, adjectives, and other adverbs and include words like “quickly” and “very.” This clear distinction between a preposition and adverb can become a bit confusing, however, in that a prepositional phrase can act as an adverb in some sentences.
One of the easiest ways for someone to understand the difference between a preposition and adverb is for him or her to first know what each type of word does. A preposition is used in a sentence to indicate the relationship between two objects or ideas, in terms of space or time. They are often positional in nature, or provide information about when something was done in relation to something else.
For example, in a statement like “The squirrel on the tree,” the word “on” is a preposition as it describes the position of the squirrel. In this example, the phrase “on the tree” is a prepositional phrase that fully answers the question “Where is the squirrel?” though “on” is the only preposition in it. In this example, “the tree” is a noun phrase and the object of the preposition.
The major difference between a preposition and adverb is that an adverb describes one particular object or action by modifying it. In a sentence like “The squirrel quickly ran up the tree,” the word “quickly” is an adverb that modifies the way in which the squirrel ran. Adverbs can also modify adjectives, such as the word “increasingly” in “increasingly scary,” and other adverbs, “very” in the phrase “very quickly.” The use of adverbs in a sentence provides information about how an action was taken, in the previous example the question of “How did the squirrel run?” is answered by the adverb “quickly.”
As individual words, a preposition and adverb are quite dissimilar, but there is one way in which they can be alike. Prepositional phrases can sometimes be used as an adverbial within a sentence. This means that they still have the form of a prepositional phrase, usually starting with a preposition that is followed by a noun phrase, but they have the function of an adverb.
In a sentence like “The squirrel ran up the tree,” the prepositional phrase is acting as an adverb. Even though it answers the question of “Where did the squirrel run?” it also acts as a modifier for the word “ran.” The prepositional phrase could be exchanged with a single-word adverb, “The squirrel ran quickly,” to demonstrate how these functions are interchangeable. A preposition and adverb are still different types of words. The preposition “on” in the statement “The squirrel on the tree,” could not be exchanged with an adverb like “happily” or “quite.”