Unofficially, there are three. The editorial board edits and lays out its pages. No official slots. Copy desk chief acts as unofficial slot. There is no career path within the desk.
Folks tend to be career copy editors.
New hires may have chosen editing. They are slowly integrated into the desk. Responsibility comes only during an absence due to vacation or illness. Copy editors take their cues from the city desk editors who basically listen to what the managing editor wants to lead with. All copy editors lay out their own assigned pages.