Adjectives are used to qualify the nouns used in the sentence. This indicates that an adjective cannot be used without a noun, while a noun can be used singularly –without an adjective modifier- in a sentence. This functional variance of each marks the differential border between them.
Noun vs Adjective
The main difference between a noun and an adjective is that noun is used to identify a person, place, idea, or object, whereas adjective is used to connote a noun modifier. Adjectives are descriptive terms used in conjunction with nouns to specifically define the noun.