What do personnel assistant, sales supervisor, sales representative and lecturer mean respectively?

hello. 1. personnel assistant. Is responsible for staff recruitment salary management attendance, an assistant in the personnel department, even lower than the Commissioner. 2. The sales supervisor is the person who manages ordinary employees. His upper level is the sales manager, and the lower level is the ordinary employees. 3. The sales representative may be an employee or a leader, and he is the person who engages in a certain business on behalf of the seller. 4. Lecturer, usually an experienced person with a high degree of professionalism, gives lectures to everyone and some people who are often trained.