What is the difference between a ‘closed’ and an ‘open’ meeting?

What is the difference between a ‘closed’ and an ‘open’ meeting?

An open meeting of A.A. is a group meeting that any member of the community, alcoholic or non-alcoholic, may attend. The only obligation is that of not disclosing the names of A.A. members outside the meeting. A closed meeting is for A.A. members only, or for those who have a drinking problem and have a desire to stop drinking. Closed meetings give members an opportunity to discuss particular phases of their alcoholic problem that can be understood best only by other alcoholics.