If you aren't sure, check the flowchart below.
Supporting characters used the PC templates, but put 'supporting character' in the category field. Named NPCs use their own template, and all their info can be found here.
Students are characters on Manta Carlos who are attending Starlight Academy. Students who are being home tutored, attending other schools, or who are attending the police academy are not considered students and would instead go in citizens. Being a student takes priority over being a citizen.
More information on students.
Staff are characters on Manta Carlos who work as faculty for Starlight Academy. This includes both teachers and non-teachers such as librarians, custodians, school doctors, etc. If a character has a civilian job and a position at Manta Carlos, they're considered staff.
More information on staff.
Citizens are everyone else, the people who live on Manta Carlos but who are not either a student or staff of Starlight Academy. Citizens will generally have a job, although a job is not mandatory to be a citizen. Characters who would not legally be considered citizens are still placed in the citizen category.
More information on citizens and businesses.