At my county/state, Division C is quite a lot more difficult. I'd say from personal experience that Div. B states is about the same difficulty as placing in Div. C regionals, but well the students are 3.5 years older, so it's really expected. Also, a major change I saw in my team and a few other teams I've talked to is that the teachers often babysit the students in Div. B, but seldom in Div. C. If you're good at Div. B, and always stay on top of things already, the transition isn't difficult

The team atmosphere changes a little. At Div. B, we really had little HW, and are just doing everything for fun. In HS, because of the increased workload all the not-so-committed members would drop out, and we would go from a 50+ Div. B club to a 20 member Div. C club. People in Div. C club are much more connected and focused, though. There's just less time for fooling around

raxu