generally a "conversion van" is the type that has a "lounge" in the back and some capt's chairs, and a raised roof.
a Class B RV is titled as an RV, and will have bed(s), toilet, cooking, shower, heat and ac battery storage and or a genny. and a roof raised enough to stand up and move around.
Lot of options as you figure out which features you want
what about your Ram, consider a camper?- these can offer many of the amenities of an RV and if you truck is heavy enough to carry it, you'd be saving alot.
many have easy electric jacks, just lift it off the bed when you are not using