Adjective
A word or group of words that modifies a noun or pronoun. Adjectives are called modifiers because they limit the words they are modifying.
Example: I'm wearing a blue shirt.
Adverb
A word or group of words that modifies a verb, adjective, or other adverb. Both Adjectives and Adverbs are modifiers, but they modify different kinds of words.
Example: She is an extremely intelligent person.