Determiners and adjectives are related in such a way that they both modify a noun or a noun phrase.
determiners are placed before nouns and introduce them to the audience.
adjectives modify nouns by providing further details about noun.
determiners cannot be graded.
adjectives can be expressed in different intensities. For instance, an object may be big, bigger, or biggest. However, it cannot be “that-est” or “the-est.”
adjectives are only optional parts of a sentence, while determiners are necessary and indispensable.