I have to admit that I'm not that up on the Buses and got that incorrect info from a personal site, thanks for the update. Any idea of MPG on both?
Here's some informstion from http://www.thebusdepot.com
1980-1983 Vanagon & Camper
The new, squarish Vanagon body style had many advantages over the Bus, and a few drawbacks. On the plus side, the Vanagon has noticably more interior room and more modern handling (particularly in heavy winds). However, some parts can be pricier, and the bus was better on rough terrain or ice. The '80-83 models used the same air-cooled motor as the late bus, although they were notably more sluggish due to increased body weight. (Also a Rabbit-Diesel powered version was offered. Drive it before you buy it. Very lethargic, but great gas mileage.) The camper interior was by now very modern, and stayed largely the same thru 1991. Now both front seats swiveled, and could face each other with a table in between to form a second dining area. Also, a larger, front loading fridge was offered, which ran on LP gas as well as AC/DC. (Fridge and stove remained optional.) Gone was the 70's walnut and plaid look, replaced with more conventional fabric and formica.
19831/2 - 1984 Vanagon & Camper
In perhaps the biggest mid-year model change in auto history, VW switched from air to water cooling in mid-83. (This change occurred in the beginning of '83 in Europe.) The new "wasserboxer" motor (basically a Beetle engine with a water jacket) is more complicated to work on than the old "bus" motor, and parts can cost more, but it 's smoother, quieter, and has more horsepower than the air-cooled version. Plus you get real heat!!
1985-1992 Vanagon & Camper
By now, power steering and air conditioning were the norm in the U.S., along with a rear wiper on most models. Also, in '86, the motor was upgraded from 1.9 liters to 2.1. The "deluxe" package with stove and fridge was now standard on most Westies, along with an upgraded GL interior (plush captains chairs with armrests, velour upholstery, etc.) Also a different poptop model was offered, with no sink, or stove, but with extra seating, a pop-out table, and a removeable "electric icebox." By 1985-1987 you could also get cruise control, power windows and locks, heated mirrors, and even four-wheel-drive (the exceptional but expensive Syncro). The Westfalia Camper was now a luxury vehicle compared to the utilitarian models of old... but was, alas, far less affordable.
Shopping Tips for Vanagon & Camper
Unlike the busses, rust is rarely structural. It tends to form on the seams between the body panels, and around the camper utility inlets on the drivers side. The air-cooled motors (thru '83) are the same as used on the '72-up Bus (see the Bus section) and have the same issues. The diesels tend toward CV joint failure. The Syncros have many unique parts (i.e. front drivetrain, driveshaft, fuel tank) that can be incredibly expensive to replace if bad. All watercooled Vanagons tend to develop cooling system and/or head gasket problems at high mileage, which can be expensive to repair if it has not been done already. Beware of coolant leaks or overheating! Let the van idle for a good half hour. The temp guage should stay under 2/3, and the radiator fan should turn on as the van heats up. Otherwise you may need anything from a flush & fill to new heads or head gaskets. Also, look for leaks at the power steering rack and at the rear heater core (run it and sniff for the sweet smell of coolant).