HR makes an initial screening phone call, then hiring manager calls if you pass the screening.
Afterwards, you're invited to a site visit to meet with a set of individuals who you're likely to encounter in your daily work if/when an offer is made to you.
I was invited to a site interview to meet with multiple interviewers on the same day. I thought the schedule was well organized, with a copy of the agenda sent to my email well ahead of my appointment. On a negative side, no offer of lunch/snacks for an interview at 12pm? Really?
During the interview itself, a handful of people (maybe 2 out of 8?) were quite pleasant to talk to, while a majority - one lady in particular - sounded like someone I wouldn't care to work with in any organization. She came across as rude and aggressive; such individuals often make team-work extremely difficult and painful. I like opinionated people, but when someone insists on always having their way, it makes for "interesting" theater. She kept on complaining about her colleagues and how they made her work difficult. She was also self-congratulatory, talking snappily about projects she "single-handedly" initiated/completed just a couple of months after she joined the company; not even a single sentence about her team making this achievement possible. Knowing that I would likely have a lot of interaction with this person on a daily basis, I began to doubt if this would be a good fit for me.
If you plan on going to an interview here, it's better to play "dumb" and pretend you're a novice so you don't intimidate the folks interviewing you. It appears to me that they want to employ people who think exactly like them, and have no "out-of-the-box" ideas. Some of the interviewers shared a few scenarios to which I naively offered probable solutions; I don't think they took too kindly to my offer of "new" ideas:). I thought an interview was an opportunity for employers to evaluate job seekers' skills by presenting them with difficult questions, and the candidates thinking "out-of-the-box" to proffer probable solutions. My candid opinion, after leaving the interview, was that this company has a culture of "speak only when specifically asked to speak" or "do as I say and don't present me with alternatives". I also observed the way everyone of them spoke about their CEO like an object of worship. It would appear this is not a place where one is allowed to have an opinion.
I went to the interview just to see what was out there (in terms of new opportunities), but after the interview, I left wondering why I had wasted my precious time. In the end, I wasn't offered the position, but even if I was offered, I would not have accepted it. Perhaps if I had been desperate for a job, I would have done my homework and tried to be that "perfect" job candidate.