It appears that the words, 'shrimp' and 'prawn' are both British in origin.
'I always thought "prawn" was the British English word for the animal that Americans call a "shrimp," and although that is the case, there is also actually a scientific difference between a shrimp and a prawn.'
'While very similar in appearance, shrimp and prawns are two different species, with different gill structures, different habitats, and a difference in taste.'
'Shrimp come from both fresh and salt water and can live in both cold and warm waters; if they came from cold waters, then they will be smaller in size. There are more saltwater than freshwater species of shrimp.'
'Prawns come from fresh water, and are much larger and meatier than shrimp, like a langoustine. Their meat is much sweeter than those of shrimp. Prawns also have bigger pincers and longer legs.'
copied from:
http://www.thekitchn.com/whats-the-difference-between-a-92489
'The terms shrimp and prawn originated in Great Britain. Shrimp is applied to smaller species, particularly species that are dorsoventrally depressed (wider than deep) with a shorter rostrum. It is the only term used for species in the family Crangonidae, such as the common shrimp or brown shrimp, Crangon crangon. Prawn is never applied to very small species. It is applied to most of the larger forms, particularly species that are laterally compressed (deeper than wide) and have a long rostrum. However, the terms are not used consistently. For example, some authors refer to Pandalus montagui as an Aesop shrimp while others refer to it as an Aesop prawn.'
'In the United States the term shrimp is used for almost all species. Prawn is less commonly used. Shrimp is the more general term, both in Britain and in North America, but most particularly in the United States. In the United States, the term prawn applies especially to larger shrimps and those that live in freshwater.'
copied from:
https://en.wikipedia.org/wiki/Prawn#Prawn_versus_shrimp
