Hi JDMWDC,
While I have no idea into all the factors that may go into the prices that are chosen by individual manufacturers … I can tell you they are different designs with different options available. The Ultimate Dreams is a finished design that has no exchange or return options (unless Amazon fulfills the order in which case a return would be subject to the Amazon large item return policy) while the Cotton Camilla has a different cover and a 120 day comfort guarantee where the top layer of latex can be removed and replaced so you can exchange your comfort layer at no cost if you make the wrong comfort choice.
You could also call them and I know they will be happy to help you compare any other differences between the two mattresses.
Phoenix