What is the difference between oysters, clams, mussels, and scallops?

They all taste different. But all belong to the same family. I am fascinated by how we value each one differently. Like, we get jewelry from oysters (pearls). Native Americans wove gloves out of the beards of mussels that knives couldn't . The scallop features in european design through the centuries. As to clams, you may have to ask someone from Boston. Should they be compared? Probably not anymore than siblings would want to be compared.