Culinarily, many people distinguish between shrimp and prawns on the basis of size. “Prawns” are considered to be larger, while shrimp are smaller

The primary difference is the gill structure. Shrimp have branching gills, while prawns have lameller gills with a platelike structure. There are a few other distinguishing features. The front pincers of shrimp are typically the largest, while prawns have bigger second pincers. Prawns also have longer legs than shrimp. These differences may seem subtle, but they indicate different steps along the evolutionary path of both creatures.