In America, what is the difference between a prawn and a shrimp?

Question

Thinking of them alive in tide pools (rockpools in UK English) rather than on the plate.

After 3 answers already received.
Shrimp in England is the Brown Shrimp, Crangon, or the deepwater Pink Shrimp Pandalus, which is a prawn. Most of the others are prawns, unless very small and then they are shrimps. In rockpools, prawns are usual.

Answer 1

As usual with common names, there is no generally accepted
distinction between the two words. Prawn, when it is used at
all in the United States, seems to refer to larger organisms.
The distinction between marine shrimp and freshwater prawns is
nonexistent here, as far as I can tell, the freshwater ones are
commonly called shrimp.Shrimp and prawn seem to be used indiscriminately for either freshwater or marine species,
except that the use of prawn is rare here.

Answer 2

In the United States, according to the 1911 Encyclopedia, the word "prawn" usually indicates a freshwater shrimp or prawn.

Answer 3

"According to Food and Agriculture Organization (FAO) of United Nations, shrimp is a seawater creature, while prawn's natural habitat is fresh water. This definition is not used by the grocery stores, fish markets, or the restaurants. Retailers commonly differentiate them by the size. A larger jumbo shrimp (Less than 25 shrimp to a pound) with head-on is normally referred to as prawn.

Scientifically, there is a difference between the two species. Both species are found caught in sea water as well as fresh water with varying sizes."

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