Adjectives vs Adverbs - English Grammar Basics | Verbal Ability (VA) & Reading Comprehension (RC) - CAT PDF Download

Key Difference:

Adjectives modify nouns or pronouns.
Adverbs modify verbs, adjectives or other adverbs.

Adjectives vs Adverbs Examples
 

1. Adverbs and Adjectives are both modifiers, so it is easy to confuse them with each other. And even more confusingly, some words sometimes act as adjectives, and sometimes act as adverbs. 
   
   Hint: Ask yourself which word is being described: adjectives always modify nouns or pronouns, but adverbs never do. 
   
   Sarah was a little sleepy. (adverb modifying adjective sleepy)
   Sarah took a little nap. (adjective modifying noun nap) 
   
    
2. Use the comparative degree of an adjective or an adverb when speaking of two thingsand the superlative degree when speaking of three or more: 
   
   This is the larger of the two rooms.
   This white one is the smallest of the three puppies. 
    

Good vs well

Good is an adjective. The adverb is well. 

Ex: My father is a good driver -> He drives well.
Your English is good -> You speak English well. 

I feel good. (psychologically / morally)
I feel well. (healthy / well being) 

Fast / Hard / Late

These words are both adjectives and adverbs: 

Lately = recently 
Have you seen Tom lately? 

Hardly = very little, almost not 
Sarah was rather unfriendly to me at the party. She hardly spoke to me.(she spoke to me very little, almost not at all) 

George and Hilda want to get married but they've only known each other for a few days. I don't think they should get married yet. They hardly know each other. (they know each other very little) 

We cannot form adverbs from adjectives ending in ly. 

Common adjectives: friendly, lively, ugly, lonely. We add the pattern in a … way/manner or fashion to make them adverb.

Friendly: In a friendly way/manner/fashion He behaves in a friendly way. 
Lively : In a lively way / manner / fashion