for my pre-med committee they are NOTHING like any of the the med school interviews i have been on so far. Basically, for me it's a demoralizing ordeal, several prof's playing good cop/bad cop. Issues on healthcare, grades, etc. Each school is different, but from my experience, they basically try and get at every point of your application to see where you stand. And if there is a hole, they'll exploit it for all it's worth. Honestly, in my case, it's done for undergrads who have no real interviewing experience and wind their nerves like crazy. I got my letter, despite fighting with the damn place for like 1 1/2 years to even consider me, and have never looked back. The pre-med office (which has never helped me) has asked me for help in my interviews for future students to use. HA!
as far as med school interviews, they've all been like conversations with people who want to really get at who you are deep down and why you want to do it. Very friendly, very casual.