What's the difference between a graphic designer & an art director?

An art director is the person that comes up with the artistical concepts. He or she works with the copy writer and the clients and comes up with the concept and then decides which approach to take. He or she is in charge of deligating responsibilities to vendors such as the photographer, graphic designers, fashion hair and makeup etc.

The graphic designer is the person that follows within the realm of what the art director has envisioned for the campaign and carries out that job.

I work in an advertising company and we use the following...

An art director is someone who thinks about what they are going to make. He or she makes a demo or sketch of the item they are going to make.

The graphic designer is the one who does the finishing of the work. The art director thinks and draws what the graphic designer has to make.

A graphic designer is one who specializes on the art or profession of using design elements (as typography and images) to convey information or create an effect.

while an art director is one who have trained eye on latest trends.