What is the difference between an adjective phrase and an adverb phrase?

An adjective phrase is a group of words that acts as an adjective in a sentence by modifying a noun (e.g., “the weathered gray house”).

An adverbial phrase (or adverb phrase) is a group of words that acts as an adverb in a sentence by modifying a verb, adjective, adverb, or entire clause (e.g., “He ran very quickly”).

Adjective phrases can contain adverbs (e.g., “the exceptionally smart dog”). To distinguish between adjective phrases and adverb phrases, think about what the phrase modifies in the sentence.