How do you distinguish and adjective from an adverb?

An adjective describes a noun, whereas an adverb describes a verb.

Ex of an adjective: Josephine is amazing with clay.

In this sentence, amazing is describing a proper noun, Josephine.

Ex of an adverb: Harvey runs quickly.

In this sentence, quickly is describing how Harvey RUNS, which is a verb.

Also: most adverbs end in -ly, so this is usually a clue on how to distinguish them.