Shrimp vs prawn is colloquial, not a scientific classification, so it varies from place to place and person to person, and depending on the specific animal we’re talking about, but in general

The ones we call shrimp tend to:

• Live in salt water
• Be smaller
• Have curled bodies
• Belong to the sub-order pleocytema
• Have plate-like girls * gills*

And the ones we call prawns tend to:

• Live in fresh water
• Be larger
• Have straight bodies
• Helong to the sub-order dendrobranghiata
• Have branching hills gills