Plums are native to Asia, America and Europe, although most plums in U.S. production are the red and yellow Japanese varieties. There are lots of types of plums, for example the European varieties are mainly purple and blue.
Plums differ from prunes in that they have a cling stone (difficult to separate from the flesh), whereas prunes have free stones (easy to remove from the flesh).
Most of the 125 varieties of prunes (with the exception of Italian Prunes) are primarily grown for drying and making prunes. Plums and prunes are the same, although not all plums can be considered prunes. The prune varieties of plums contain a very high sugar content to enable them to dry without becoming fermented while the pip is still in the fruit. The name prunes was changed to dried plums as it is more descriptive for those who are not familiar with the fact that prunes are in fact just fresh plums that are dried. Either way, raw or cooked plums taste awesome!