Some words are combined with adverb particles in order to build idiomatic expressions we call phrasal verbs. As adverb particles seem the same as prepositions it is necessary to see whether they are tied to their verbs or a noun/pronoun. If they are tied to a verb they are called adverb particles, otherwise they are called prepositions. See the examples:
*Peter has put his jacket on. -adverb particle is in red (as it is tied to the verb put to form a phrasal verb)
*We drove to the supermarket. (closely tied to the noun- supermarket, so we call it preposition)
Note: Some adverb particles and prepositions are the same words and we need to see in which context they occur in order to decide whether they belong to adverb particles or prepositions.