Utility Patent 
A utility patent differs from a design patent in that it protects the mechanical, electrical or chemical aspects of an invention.
Utility patents also may cover newly discovered uses of a known drug, methods of using an apparatus or using a chemical composition;
articles of manufacture; a new process; certain methods of doing business; and software source code.
A design patent is more limited in its protection.
It only covers the "ornamental" aspects or "look" of an item, not its utilitarian or mechanical aspects, described above.