This is from RIVA'S consumer site.
Type B Motorhome
"Commonly called van campers, Type B Motorhomes are built using automotive manufactured van or panel-truck shells. Van campers drive more like the family car, but offer the comforts and conveniences of home on the road."
If it started out as a van, and converted then it's a Class B, if it has no bedroom, kitchen, and bathroom, then it's a Camper Van.
A B+ is just a marketing term for a small Type/Class C.
Type C Motorhome
"Type C Motorhomes are built on an automotive van frame (cut-away chassis) with a wider body section attached to the original cab section. Many Type C Motorhomes are easily recognizable by the over-the-cab area that is often an optional sleeping area. Amenities are similar to those in conventional motorhomes."
Go RvingThese are the definitions that RV.Net uses for this web site.