What’s the difference between starchy and waxy potatoes?

Starchy potatoes have low moisture and sugar levels, but a high starch content. This makes them the better potato for baked, mashed, fried, or roasted potatoes. With the low sugar content they collapse better.

Waxy potatoes are just the opposite, with high moisture levels and low starch levels. They are good candidates for salads or casseroles because they hold their shape well when cooking.

Source: National Potato Council