I've had 2 interviews and they were quite different.
One (the city service) was your basic, sit-down, question-and-answer. There were only 8 questions, it took maybe 10 minutes or so. No skills test or written test. Never got a second interview with them.
At AMR, I had to take a written test in order to even apply. No leads yet with them.
At the private company where I got an interview, it was a "mass screening" for applicants, they were not even hiring at the time but just called a bunch of people in to pre-screen them. There were about 12 other people there. We all filled out paperwork in one room, then groups of three did a rather easy 'fitness test', then we interviewed individually. There were only 4 or 5 questions and the interviewer didn't even seem like he was listening. I never heard back from them either.
Good luck.