I'm with AsheGuy, there is nothing blurry about the difference between a B and C. It has now been clearly explained. I traded my first B for a small C and am now back in a B. (changes due to different needs)
I found two comments in this thread confusing. One was the idea that a Class B doesn't have a generator. Even in 2004 when I bought my first B, it was thought odd that I ordered it without a generator and the dealer pushed me to at least put in the prep package because he was certain that the next purchaser would want one. (and sure enough... the first thing the buyer did was put one in)
The other was comments that they didn't see B's on the road. I completely disagree with that. When I had my first one 13 years ago, I did rarely see one. Now I see them often... every day when I am traveling between MN and AZ I see a few. Lots of Sprinters which often don't really look like RVs since B people tend to NOT have those flashy (and I think ugly) stripes all over them. My little RT has no stripes and no words painted on it anywhere. It is just a tallish pretty silver van... with only the distinctive 3 windows on the front to show that it is a Roadtrek.
And I agree that most of the B people seem to be over on Facebook, which is an irritating and highly inefficient way to discuss RVs and their maintenance issues. They also tend to be divided by brand.