Programs like mine suck that make you take some of the 2nd year med school courses in one sense, but then again, I've never had so much free time. I went to the Pathology course the first day to pick up the syllabus, then I never went again because the topics and textbook were the same as in dental school. I'm not saying that I remembered all those details, but having already seen the material once made it much easier.
I definately knew more than the regular med students in certain areas, but not in other areas because I didn't care since I had already gone through the match. On my trauma/surgery rotation they made me "face-lac-boy" because I had already sewn more facial lacerations than any of the general surgery residents (because they generally don't sew faces). This saved time on patients with no underlying bony fractures.
As far as the differential diagnosis for anemia, etc. the med students definately knew more. Probably because I didn't care enough about those things to read about them. Now that I think about it, I was a hard worker in areas I liked, but then I was a lazy slug when I was bored.