Onur Cobanli explains:
When you make something totally different or new, that is art, unless it improves something; if it both improves something and also is totally new, that is good design; it is art, design and engineering, however when you do not make something new, but improve upon an existing product, service or offering, it is design. Design is always about making things better, and never focuses on (but welcomes) making things different, unless the difference is a functional requirement!.