Just like any other company, first to have an interview with you is the HR. They will refer you to the Department Head/Manager to review your application. Once accepted, you will proceed with the interview with the Dept Head. The difficulty of the interview is I can say that it depends on the dept head, as for my experience, it was okay and smooth. My manager was very welcoming, he was not too intimidating, will ask you questions about yourself and then why you wanted to apply and what do you know about the position. It was basically all that.