Hi Pegabo,
While it’s not possible to quantify the sleeping temperature of a mattress for a particular person or know for certain how two mattresses will compare in terms of temperature regulation for a particular person (there is no standardized testing for this) … there is more about the many variables that can affect the sleeping temperature of a mattress in post #2 here that can help you choose the types of materials that are most likely to keep you in a comfortable temperature range.
The layers that are closest to you will have a bigger effect on sleeping temperature than layers that are farther away from you so upper layers will have a bigger effect than deeper layers.
In very general terms (because there are so many other variables involved) … latex is the most breathable and “temperature neutral” of all the foam materials.
Gel foam materials tend to have a cooler surface temperature when you touch them but the benefits of gel materials tends to be short term so while the gel can help with cooling when you first go to sleep at night, once temperatures equalize then the insulating properties of the base foam material become dominant. There is more about gel foams in post #2 here and the posts it links to.
Natural fibers such as wool are better temperature regulators than foam materials because they are very breathable and moisture wicking and wool in particular does a great job of storing moisture inside the fiber and away from the skin.
Innersprings of course are highly breathable but in most cases they are used deeper in the mattress so their effect on temperature is less than with layers that are closer to the top of the mattress.
Phoenix