What is the difference between worker bees and drone bees, and are there any other types of bees?

Workers are the smallest of the bee castes, but are by far the most numerous. All workers are female, and normally incapable of reproduction. They are unable to mate, but in a hopelessly queenless colony, workers may begin to lay unfertilized eggs, which develop into drones. Drones are the male honey bees. The only function of a drone is to fertilize a young queen bee. Queen bee function in the hive is one of production. Queen bee is normally the only reproductive female in the colony. Egg-laying begins in early spring, initiated when the first fresh pollen is brought home by the workers. Egg production will continue until fall, or as long as pollen is available. So there are three types of bees: workers, drones and a queen bee.