If they're flying you out, then it's likely a real interview. If you have to provide your own transportation, who knows. But like rickair said, if it's at a hotel it's probably just a meet n' greet type thing.
That said, I remember being invited to a group interview in SLC. Since I had to provide my own transportation (from CA), I decided to not go. About a week after the event, I received an invitation to a real interview complete with positive space travel to SLC.
As for the interview itself, the gouges that I've seen are pretty much right on. No tricks.... just be prepared for technical talk, know your Jepps and the systems of what you've been flying. Be able to fly a few approaches and a hold /A.