There are about 30 different varieties that will be available at the supermarket at different times during the summer and early fall. Ranging in color from black to pale yellow, and from sweet to tart in flavor, you'll only find each of these special varieties for a short period of time, so when you see a new one, be sure to take the opportunity to try it.
Although plums are native to Asia, Europe and America, most U. S. production is in the Japanese varieties which are red and yellow (European varieties are blue and purple).
The difference between plums and prunes is small. Plums are clingstone (the pit does not separate easily from the flesh) and prunes are freestone. While there are at least 125 prune varieties, most (except for Italian prunes) are grown for drying.