What is the difference between art and popular culture?

Continuing my exploration into So, why is this art? I will examine the seventh of the key points:
What is the difference between art and popular culture?
The Contemporary explores this question thusly:

...For some artists, the overwhelming presence of consumer products and popular culture caused them to question the lack of connection between art and real life. The term "high" art was used to refer to painting, sculpture, and other works that followed the accepted theories of art at the time and that we would expect to see exhibited in galleries and museums. "Low" art or popular culture referred to imagery made for the general public...

Traditionally, the art world did not consider popular culture as a worthy source of art. Some artists rebelled... to break down the barriers between high art and the objects we live with and to make people think about the values of the culture around them.

I have spoken about "high" and "low" culture before in A Matter of Taste, but I will reiterate once again that I think diversity of expression should be celebrated and that we need art that builds on history and tradition, just as we need art that confronts it, just as we need art that caters to the masses... It takes all kinds, and I would like for everyone to be able to make their voices heard and expressions known should they desire to do so.