A conference has two structures running at the same time. One runs the debate. The other runs the event around it.
Working out which structure your question belongs to is the fastest way to find the right person to ask.
A conference needs adults who hold the responsibility a student cannot. They deal with the venue, the money, safeguarding, and the relationship with the schools that send children. They appoint the student team and oversee it. They do not run debate.
This group stays in place from one year to the next. That is what gives a conference its continuity.
In MEDIMUN, this group is the executive board. It is made up of the Senior Directors and the Directors. All of them are teachers. See The executive board.
Below that sits the student leadership, usually called the Secretariat. They lead the conference academically. They oversee the committees, settle problems a chair cannot settle alone, and lead the joint session on the final day.
The student leadership changes every year, because its members are students in their last years at school.
In MEDIMUN, the Secretariat is the Secretary-General, the President of the General Assembly, the Deputy Secretary-General and the Deputy President of the General Assembly. See The Secretariat.
Debate happens in committees. Each committee has a team of chairs who run it and a room of delegates who debate in it.
In MEDIMUN, a session has seven or eight committees. Four are General Assemblies. The rest are Security Councils and Special Committees. See The conference at a glance.
Everything that is not debate is done by departments. A department has a manager who leads it and members who do the work.
In MEDIMUN, there are nine departments. Admin Staff. Approval Panel. Food and Catering. Information Technology. MediNews and Social Media. Photography. Preparations. Public Information. Sales and Funding. At most conferences, Administrative Staff is one large group that does everything operational. MEDIMUN has split that work into separate departments, each with its own specialised role, its own manager and its own members. The Admin Staff department still exists, and its only responsibility is in-committee logistics. See Departments overview.
Each department is answerable to named people above its manager. See Departmental responsibility.
Delegates are not staff. They come to the conference to debate. They are not part of the structure that runs it.
In MEDIMUN, a session has around 400 delegates, aged 15 to 19, and around 100 students running the conference as staff.
Delegates arrive as part of a school delegation, with a teacher from their own school. That teacher is a school director. A school director is responsible for their own students. They are not staff of the conference.
In MEDIMUN, a session has around 60 school directors. Only schools apply to attend. An individual student cannot register on their own. See The school director role.
Everyone who runs the conference is staff. Only some of them are Student Officers.
A Student Officer is a student who runs part of the conference. The Secretariat, the chairs and the managers are Student Officers. Members are staff, but they are not Student Officers. They are Administrative Staff. Delegates are neither.
This is stated wrongly often. Being staff and being a Student Officer are two different things. See What is a Student Officer.
If somebody has held more than one role. A student may chair one year and manage a department the next. What they are is decided by the role they hold in the session you are looking at, not by what they did before.
If you are unsure. Work out which layer your question belongs to. A question about the rules of debate goes to your chair. A question about your school's place at the conference goes to your school director. A question about how a department works goes to its manager.