please differentiate in the most simplest way regarding
adjective and adverb
Adjectives and adverbs both modify -- but they modify different things.
Adjectives modify nouns: "This is a big book".
Adverbs modify verbs: "She walks slowly". Adverbs can sometimes also modify adjectives: "This is a very big book"; or even whole sentences: "Unfortunately, he had an accident".
(Some books say "qualify" instead of "modify". It's the same thing.)