The answer is that there isn't an intrinsic difference between jumbo prawns calories and shrimps calories - but there may be a big difference between calories between one variety or harvest of jumbo prawns (or jumbo shrimps) vs another. The amount of water weight in jumbo shrimps and jumbo prawns varies tremendously, and in spite of nutritional labels on packages of shrimps and prawns (when they are there at all), there may be a big difference in calories from one sample of prawns to another. For example, typically for 3 modest sized jumbo prawns each about 1 oz a typical calorie count is about 110 calories. This can be more like 80 calories if the prawns have a lot water content, and might be more like 130 calories if they have little water. You can only use jumbo prawns calorie counter as VERY approximate indicators of jumbo prawns calories.