Design

In general terms, a “utility patent” protects the way an article is used
and works (35 U.S.C. 101), while a “design patent” protects the way an
article looks (35 U.S.C. 171). The ornamental appearance for an article
includes its shape/configuration or surface ornamentation upon the
article, or both. Both design and utility patents may be obtained on an
article of invention resides both in its utility and ornamental appearance.
While utility and design patents afford legally separate protection, the
utility and ornamentality of an article may not be easily separable. An
invention may have a blend of functional aspect and ornamental design.

In a design patent application, the subject matter which is the design
embodied in or applied to an article of manufacture (or portion thereof)
and not the article itself. This refers not to the design of the article, but to
the design for an article, and is inclusive of ornamental designs of all
kinds including surface ornamentation as well as configuration of goods.
The design for an article consists of the visual characteristics embodied
in or applied to an article.
Since a design is manifested in appearance, the subject matter of a
design patent application may relate to the configuration or shape of an
article, the combination of configuration and surface ornamentation.
Design is inseparable from the article to which it is applied and cannot
exist alone merely as a scheme of surface ornamentation. It must be a
definite, preconceived thing, capable of reproduction and not merely the
chance result of a method.

35 U.S.C. § 171. Patents for Designs
Whoever invents any new, original and ornamental design for an
article of manufacture may obtain a patent therefore, subject to the
conditions and requirements of this title. The provisions of this title
relating to patents for inventions shall apply to patents for designs, except as otherwise
provided.