Ah, welcome to the mattress industry, aka "the land of confusion." Make no mistake, your confusion is by design. They don't want you shopping their products.

Looks like those actually are all different models, so they are not quite the same. For instance, the Shakespeare has a blended latex band in the center third of the mattress while the Pierport and Castleton do not. The Castleton appears to be a Macy's "exclusive" and the specs are different as well as well as a higher price (at least online, probably much less in a store.) However, they are all using a pretty similar build with most of the same types of self-branded components, AirCool foam and so on as well as the Beautyrest pocketed coils.

One of the biggest rackets of this industry is the use of 50 million different models from the same company on a floor so they can utilize a huge pricing spread. The big secret is that most of the "top of the line" models are using the exact same stuff as the cheaper models, maybe just "more" of it.

Also, be sure you're comparing the same types of surface feels, whether it's a "firm, plush or pillowtop" and so forth. You can ask the salesman for a spec sheet that you can take with you as well.