String beans and snap beans are both members of the legume family, but they are harvested in very different ways. String beans are grown on a trellis or poles and picked when they are tender. Snap beans are grown on a trellis or poles and harvested when the pods are mature. String beans are available in many colors, while snap beans come in only one color. String beans have long thin pods and snap beans have short thick pods.
String beans have more straight, solid, cylindrical shape. Snap beans have more curved, tapered, and wavy shape. String beans are often blanched (cooked but not boiled) and then frozen.