It is also interesting to note that Secretary is, like Superintendent, a word that can describe very senior or very junior positions.
A secretary can be a person who answers the phone, types letters, and does paperwork for you at the office. Or, in the context of a minister but in a republic, a secretary can be someone who is in the top members of cabinet in a government (e.g. Secretary of State).
Superintendent, at least here in Canada, can be similarly ambiguous. The word can describe the person who is custodian of a school (the janitor or caretaker used to be called the superintendent) or, it can describe someone so senior that Principal Teachers (principals or headmasters) report to them, and are governed by them.