A campaign is a long lasting game of interlocking story arcs (adventures, chronicles, runs, what have you) that lead the characters to one goal. Just going around and completing adventures without a final goal, is not a campaign, it may be a story, just not a campaign. Solomon Kane is a good example. He is a landless wanderer. He goes on multiple adventures, however he doesn't have a overarching goal. He believes in being pious and puritan to the point that he may be killed for believing such, but that is not a goal it is his personality. Solomon Kane also wants to defeat evil and that is why he wanders, but that is motivation, not a goal.