Organizers are people who fill an organizer role position. Registrations For each person who registers for an event, we record a bunch of information. This helps the organizations understand who is coming to their events and why. It also helps the organization accomodate its attendees' needs and group them together. There is one registration for each person who wants to attend.
Registrations can have different states.
For example, a registration may be wait-listed because there are already too many registrations for a particular event. Or, a registration may be canceled. An order is a set of registrations. Typically, when a person registers himself for an event, he will create one order containing his single registration. But, there may be an individual who wishes to register multiple people at once.