Campaign adviser Chris Lehane uses an analogy in the article for what the events look like. They "have been shaped as 'mini town-halls' so far, Lehane explained, where attendees get one-on-one time with Clinton so that she can establish relationships with the mid-level donors who will likely not write headline-grabbing checks but will contribute steadily over the coming months."
Mini town halls! So to flesh out the various amounts of access the campaign grants:
TIER 1: Campaign donors. Access to the candidate one-on-one, with Clinton fielding questions and sticking around to make sure she can spend time with them.
TIER 2a: Regular people attending campaign events. At events in Iowa and New Hampshire, Clinton's team and hosting partners have identified particular individuals to sit and talk with the candidate in front of cameras. Clinton asks and answers questions in a formal setting, for an articulated period of time.
TIER 2b: Regular people waiting for a glimpse. At many campaign stops, people wait outside for the chance to meet and shake hands with the candidate. Sometimes, they get that chance. On rare occasions, they get to appear in ads for the privilege.
TIER 3: The press. The press gets to talk to Clinton every 40,000 minutes or so. Then they get a handful of questions.
It is almost as though this system reflects the extent to which the candidate and her staff value or find useful the people in each level.