Under the Forest River umbrella of brands you will find a wide variety of price points. They make everything from entry level units for people that need a low cost unit all the way up to luxury units that are designed for full time living. As you might expect, the quality and features are very much related to price.
As Bama Rambler mentioned, there is some duplication of brands and I believe some of that is so they can have different color schemes and such, but another reason is so that dealers that are close to each other can carry different brands.
If you end up seeing similar floor plans that vary widely in price, and wonder why, you will need to investigate things such as what materials are used in construction. One unit may feature a lot of wood in the walls and floor while another one uses a lot of aluminum, etc. There are a lot of things that can affect the price of an RV that aren't readily apparent until you do a bit of research and comparing.