Main Difference
The main difference between Adjective and Adverb is that the Adjective is a part of speech that describes a noun or pronoun and Adverb is a word that modifies a verb, adjective, or another adverb.
Adjective
In linguistics, an adjective (abbreviated adj) is a word whose main role is to modify/ describe a noun or noun phrase. Its semantic role is to change information given by the noun.
Adjectives are one of the main parts of speech of the English language, although historically they were classed together with nouns. Certain words that were traditionally considered to be adjectives, including the, this, my, etc., are today usually classed separately, as determiners.
Adverb
An adverb is a word that modifies a verb, adjective, determiner, clause, preposition, or sentence. Adverbs typically express manner, place, time, frequency, degree, level of certainty, etc., answering questions such as how?, in what way?, when?, where?, and to what extent?. This function is called the adverbial function, and may be realized by single words (adverbs) or by multi-word expressions (adverbial phrases and adverbial clauses).
Adverbs are traditionally regarded as one of the parts of speech. However, modern linguists note that the term “adverb” has come to be used as a kind of “catch-all” category, used to classify words with various different types of syntactic behavior, not necessarily having much in common except that they do not fit into any of the other available categories (noun, adjective, preposition, etc.)
Adjective (noun)
A modifies a noun or describes a noun’s referent.
“The words “big” and “heavy” are English adjectives.”
Adjective (noun)
A dependent; an accessory.
Adjective (adjective)
Incapable of independent function.
“dependent|derivative”
Adjective (adjective)
Adjectival; pertaining to or functioning as an adjective.
“adjectival”
Adjective (adjective)
Applying to methods of enforcement and rules of procedure.
“procedural”
“substantive”
Adjective (adjective)
Needing the use of a mordant to be made fast to that which is being dyed.
“substantive”
Adjective (verb)
To make an adjective of; to form or convert into an adjective.
Adverb (noun)
A modifies a verb, adjective, other adverbs, or various other types of words, phrases, or clauses.
“(modifying a verb) ux|en|I often went outside hiking during my stay in Japan.”
“(modifying an adjective) ux|en|It was often cold outside.”
“(modifying another adverb) ux|en|Not often.”
Adverb (verb)
To make into or become an adverb.
Adverb (noun)
a word or phrase that modifies or qualifies an adjective, verb, or other adverb or a word group, expressing a relation of place, time, circumstance, manner, cause, degree, etc. (e.g., gently, quite, then, there).