Setting-Settings are the broadest spaces in the Mind Weave location structure. A setting is merely the terrain, politics, etc. of an area designated for Mind Weave campaigns to take place. Without a specific campaign selected for it, a setting is nothing more than a rough sandbox for the players, this is also a valid way to play.
Rich Burlew explains what I mean by a setting quite well here.
Campaign-A campaign is a specific series of events, forces, and motivations that within a setting motivate a story for the players to follow with their characters. When a campaign is specified, it includes NPCs to help guide the players and to oppose them, as well as specific hooks to hint at the purpose of the campaign.