Hi Immi,
It would depend on the specific mattresses you are comparing and on the materials inside them. Even some of the Dreamfoam mattresses use higher quality materials than some of the others but in general terms Brooklyn Bedding uses some of the same type and quality of materials in their mattresses (such as Talalay latex) as Dreamfoam but they they also use some higher quality materials such as the polyfoam base layers or memory foam in some of their mattresses or use materials (such as wool) in their quilting which isn’t in most of the Dreamfoam mattresses.
As you know they are sister companies with common ownership and there are some general comments about Brooklyn Bedding and Dreamfoam and how they compare in posts #4 here and in post #3 here.
Phoenix