The Organizing Committee is the group responsible for organizing an entire conference for a single year. It is often made up of a Program Committee, Workshop Chairs, Virtual Chairs, Tutorial Chairs, and several other chairs depending on the particular conference.
The program committee is responsible for the main conference focusing on the peer review process for accepting papers and also deciding the format of the main conference.
The workshop chairs select the workshops and support the workshop organizers developing their workshops. Workshops may include experimental organizing and information communication techniques that may eventually be taken up by an entire conference.
Since the COVID-19 pandemic forced the conferences to become virtual (and eventually hybrid) the virtual chairs focus on developing the virtual communication techniques for an online conference. Some techniques developed for online conferences include [Zoom], [RocketChat], [Gather Town], and [Topia].
The Tutorial chairs select the tutorials for a conference and support the tutorial organizers in developing their content.
A conference may have many other chairs which are responsible for various parts of a conference.