The descriptions are different. There are two mattresses: the Contour Select and the Cloud Supreme. The pricing ($1,399.99 and $1,599.99 respectively) suggest the Cloud Supreme is the "better" mattress however Costco and Tempurpedic have defined this. For this I agree we need some fine print here to tell the difference. Since this is memory foam my guess is the Cloud Supreme is thicker.

The other two are the same mattresses, but this time in "sets." In my experience buying mattresses a set means the mattress also comes with the box spring and looking at the pictures you can see that this appears to be the case. The first two pictures have a single mattress and the second two pictures have a mattress plus something else.