So what was the game store owner's definition?
He wanted, though he didn't say it at first, to have another day on the schedule to advertise for AL play but instead of the 2-4 hour adventures it was running to have a day for one of the hardback adventures.
To me, running the hardback adventures doesn't make it a "campaign" if, like in AL, the players and characters can come and go as they please. And running the AL 2-4 hour adventures doesn't make it not-a-campaign simply by being 2-4 hour adventures.
So I started what I considered a "campaign" that currently has a too-large party of seven, though we've not actually had seven at any one session (hooray for the holidays!). Then I no longer was recruiting new players, because I already had too many. But the owner was still advertising the game as "open play" even if that wouldn't fit my idea of a campaign.