What is the difference between a dessert plum and a culinary plum?
Most plums can be used for both cooking or eating fresh. However generally speaking, dessert plums - when fully ripe - have a higher sugar content than culinary plums, whilst dual-purpose plums, such as Victoria, have an intermediate sugar content.
However it is a bit more complicated than that. The best-flavoured plums for eating fresh are not just sweet, they have a balance of sweetness, sharpness, juiciness and other subtle components which make them pleasurable to eat. These plums are often from the gage sub-family, or are true plums which have gages in their ancestry.
Good culinary plums may be less good to eat fresh but they are desirable because they respond well to heating and cooking. The dual-purpose Victoria plum is not as acidic as some purely culinary varieties, but succeeds as one of the best culinary plums because it cooks down to a very attractive and well-flavoured puree.
Damsons are another example, not particularly great to eat fresh, but quite special when cooked.