Prunes are basically plums that have been dried naturally in the sun without undergoing any fermentation process. Plums and prunes are impressively high in nutrients. They contain over 15 different vitamins and minerals, in addition to fiber and antioxidants. Overall, the vitamin and mineral content of one serving of plums and prunes differs slightly. Prunes contain more vitamin K than plums and are somewhat higher in B vitamins and minerals. They are known for improving several health conditions, including constipation and osteoporosis.