Hi Talkoran,
“Comfort layers” and “support layers” are just terms of convenience and have no specific definition. Comfort layers are the layers that are mostly responsible for the “feel” and pressure relief of a mattress and would generally be the top 3" to 6" of a mattress (depending on your weight and on how deeply you compress the mattress). Support layers are the deepest layers of a mattress that are mostly responsible for the primary or “deep support” of a mattress. Middle layers or “transition layers” can affect both the comfort and support of a mattress and perform some of the functions of both.
There is also more about primary or “deep” support and secondary or “surface” support and their relationship to firmness and pressure relief and the “roles” of different layers in a mattress in post #2 here and in post #4 here that may also be helpful in clarifying the difference between “support” and “pressure relief” and “feel” that may be useful as well.
I would also keep in mind that if you are testing a mattress locally then with careful testing (using the testing guidelines in the tutorial) your body will tell you whether a specific mattress is a good “match” for you in terms of PPP regardless of whether you know anything about the specific firmness or ILD of each layer in the mattress.
Phoenix