department head; section chief; director
In a company or organization, the person in charge of a 部 (department/section). Typically a mid-to-senior management position.
He was promoted to head of the sales department.
部長、この企画についてご意見をいただけますか。
Department head, could I get your opinion on this project?
club president; team captain
In a school setting, the student who leads a club or sports team. Often elected or appointed by members.
私は高校でサッカー部の部長を務めていた。
I served as captain of the soccer club in high school.
部長として、新入部員の勧誘に力を入れた。
As club president, I focused on recruiting new members.
He will become the head of the sales department starting next month.
She took up the position of head of the development department last year.
He served as captain of the soccer club for three years.
He was appointed as the new department head.
部長 is a specific corporate title for the head of a department, while チーフ is a looser, more informal term that can apply to any small team or project.
社長 is the head of the entire company, whereas 部長 is only a department head, several levels below 社長 in the corporate hierarchy.
assistant to the general manager; staff attached to the department head
revised by section chief; inspected by department head