Any bean in Phaseolus family can be used in all three stages. Those commonly used for snap beans have tender fleshy pods. They are not as easily shelled as those designed as shelled beans. Shellies are simply beans shelled at the mature stage, but before they dry.(green shelled beans) Limas and other types are often used at this stage. Common beans used in this manner are frequently dual purpose beans. Not as tender or as fleshy as designated snap beans, but still suitable as snap beans.Example Horticultural types. Dry beans are completely dried on the vine. Cultivars specifically for this purpose have thin tough pods, that are not too good as snap beans, but are easily shelled as dry beans. Navy beans, Great Northern are examples.
Vendors will usually list as snap beans, dual purpose beans or dry beans.

Here is a link that might be useful: Bean categories

I grow many kinds of shelly beans each year and they are a favorite of mine.

There was a shelly thread that you may find interesting. - Dick

Here is a link that might be useful: Shelly Beans