Another jargon tutorial:

If the circus is coming to town and you paint a sign saying, "Circus Coming to the Fairgrounds on Saturday," that's advertising.

If you put the sign on the back of an elephant and walk it into town, that's promotion.

If the elephant walks through the mayor's flower bed, that's publicity.

If the town's citizens go to the circus, you show them the many entertainment booths, explain how much fun they'll have spending money at the booths, answer their questions and ultimately, they spend a lot at the circus, that's sales.