For starters, you may want to let RV Trader and RVT.com do some of the work for you.
Use their advanced search feature, fifth wheel, Forest River, and then the sub brands you listed and even the model numbers. Let them show you the range of prices and you have your answer as much as that can be answered.
They build almost identical floorplans under many different names. With some, as the materials improve, prices increase, (ie; corian countertop vs laminate) The company doesnt always increase the time allowed for assembly. So the price points change based on the cost of the materials.
In general with most low to mid priced lines the changes will revolve around the following
Outer skin and framing. Alum frame and glass skin vs wood frame and luan with alum siding.
Wood cabinetry vs plywood vs particle board.
Flooring, particle board and foam vs Tongue and groove wood OSB.
Solid surface countertop vs formica.
Higher priced units may get bigger tanks, which means frames, axles, etc all have to be slightly heavier to carry the increased weight.
While all brands use bascically similar appliances, as price point increases, use of slightly larger reefers, and furnaces will occur.
But with every single aspect of the unit being planned to the n'th degree for cost and weight savings, Quality control, which is a cost, that doesnt add a single inch to the size, or lighten the unit by a single pound, gets minimal attention.
