Lux (What is Art)

Lux is a Wellington Night Light Festival "turns Wellington’s waterfront and laneways into a captivating celebration of light, art, technology and design."

 http://lux.org.nz/

Some of the image take are of the art projects, however some of these images are also beautiful lights around the projects, that help to light the streets on a day to day bases. Can you tell the difference?  So I guess this begs the question what is art?