90% of all patents issued by the U.S. Patent office are utility patents. A utility patent is for the invention of a new process, machine, product or composition of matter; or a useful improvement of one of those things. A utility patent typically protects the owner against others making, selling or using their invention for a period of 20 years in the U.S.
A design patent is issued for a new or original design embodied in or applied to a product. In other words, a design patent is specific to ornamental aspects of a product. This type of patent protects the owner for a period of 14 years, but only for ornamental features, not for functional features.