Hi tarpon21,
Like apples compare to oranges … they are very different materials. There is more about polyfoam here and here and there is more about the pros and cons of memory foam here and the pros and cons of latex here (for reference). Polyfoam is a fast response material with no “memory” and isn’t temperature sensitive and memory foam is a slow response material (the kind that leaves a “hand print” for a few seconds when you press on it) that is temperature sensitive.
Memory foam and latex are “specialty foams” which are more costly than polyfoam which is a lower cost material than either. The best way to decide how you feel about either one would be your own personal experience.
The choice between them is a preference. For those that prefer memory foam then it would certainly be worth the extra cost and for those that don’t like memory foam then it wouldn’t. Memory foam tends to be more of a “love it or hate it” material.
Tempurpedic is a memory foam mattress which means that it uses several inches of memory foam for the comfort layers (the amount and density depends on the model) and polyfoam for the support layers (memory foam is too soft to use in support layers). If you know the Tempurpedic model then I would probably be able to provide the specs but memory foam specs are different from polyfoam specs so the densities of each one aren’t comparable. For example a 3 lb memory foam would be low quality but a 3 lb polyfoam would be a very high quality material. One of the links in the tutorial post is the foam density guidelines I would suggest using here.
Tempurpedic mattresses use good quality foams (either memory foam or polyfoam) in most (but not all) of their mattresses and the 12 in 1 uses good quality polyfoam but doesn’t have any memory foam.
Phoenix