What is a split pea? What is the difference between split peas and green peas?
Both come from the same type of pea (Pisum Sativum), the only difference between them is how they are processed. With regular green peas, no processing take place other than preservation (none in the case of fresh or frozen, pasteurizing in the case of canned). With split green peas, their processing is more extensive. First they are peeled - removing and discarding the outer layer of skin (which does contain valuable antioxidants). Next, they allowed to dry - either naturally or with the help of low heat. This causes a split to naturally occur in the cotyledon, which is a major part of the embryo within the seed. Some manufacturers will exaggerate the splitting with presses and other mechanical methods.
The one benefit split peas offer versus the fresh is that they are shelf-stable and therefore much more versatile, not to mention cheaper. Though if you have a choice between the two, fresh peas will offer more overall nutritional value.
USDA Database for the Oxygen Radical Absorbance Capacity (ORAC) of Selected Foods, Release 2 - Prepared by Nutrient Data Laboratory, Beltsville Human Nutrition Research Center (BHNRC), Agricultural Research Service (ARS), U.S. Department of Agriculture (USDA) - May 2010