Hi nap101,
They would be the best source of guidance about the specific differences between them but it would come down to some combination of any differences in the cost of the materials and components in each mattress (they are similar but not the same) and possibly the margins that are built in to the price of each of them.
While I can’t speak to any differences between them in terms of comfort, firmness, or PPP … neither one has any lower quality materials or weak links in the design so they would be closely comparable in terms of durability.
Once you have narrowed down your options to a list of finalists that are all choices between “good and good” (which it seems they are) and none of them have any lower quality materials or “weak links” in their design relative to your weight range (which they don’t) and if there are no clear winners between them (which is usually a good indication that you have done some very good research) then you are in the fortunate position that any of them would likely be a suitable choice and post #2 here can help you make a final choice based on your local testing or mattresses you have slept well on, your more detailed conversations about each of them, your confidence about PPP and the suitability of each one, their prices, your preferences for different types of materials, the options you have after a purchase to fine tune the mattress or exchange or return the mattress or individual layers, any additional extras that are part of each purchase, and on “informed best judgement” based on all the other objective, subjective, and intangible parts of your personal value equation that are most important to you.
If there is really little difference between them that would affect well you sleep on each of them or on how long you will sleep well and if there aren’t any other obvious differences between them based on all the other parts of your personal value equation that are important or compelling to you would the more costly mattress really be worth the difference in cost?
Phoenix