What are the advantages of using Gram stain over a simple stain?

Gram stain can differentiate two types of bacteria. (Gram-positive and Gram-negative).

Explanation:

The Gram stain is used in bacteria and allows the observer to get the first character. With this type of stain, gram-positives stain purple because of a thick coat of peptidoglycan and gram-negatives stain more pink because their peptidoglycan wall is thinner, and they have an outer membrane, and therefore the pigments won't add as they do in gram-negatives.