IMO, there's no difference in the maintenance between a "B" and a "C" since they both have the same systems. About the only thing that would be easier on a B is washing it? A true B is definitely, clearly an RV, which is why there's a whole sub-culture of people converting cargo vans for "stealth" camping. It's almost guaranteed to not be allowed in any neighborhood that has HOA rules.
But if you want to live fulltime, all the amenities that come with an RV are nice, like a flushing toilet, shower, AC and furnace. You will get a TON more room/storage in a Class C, and they tend to be cheaper; but a Class B is narrower, shorter, (easier to drive) and can usually be parked just about any place a large truck would fit.
Having owned and loved a 28' Class C for a decade; and now driving a largish Transit conversion van, there's really not much difference in driving them. They both have limited visibility, are affected by strong crosswinds; and you always have to be mindful of how tall your vehicle is. The biggest difference is how fast my van is.....LOL! (My "9-foot tall Ferrari")
Deb