Hi cado212,
You’re right that I can’t feel what you feel or know what you will feel on any particular mattress (especially since I have no personal experience with either of them so I don’t even know how they would feel for me much less someone else) but if both mattresses had the same support core and cover and the only difference between them was that the 11" mattress had an additional inch of latex in the same firmness level on each side then the 11" mattress would be softer and for most people more pressure relieving (pressure relief and support are opposites) but would also “allow” the heavier parts of the body to sink in a little more deeply and for some people could be a little more risky in terms of primary support and alignment (although with only a 2" comfort layer in 24 ILD over a 36 ILD core this would be less likely for most people). Many side sleepers would prefer the version with thicker layers.
There is more about primary support, secondary support, and their relationship to pressure relief in post #4 here and in post #2 here.
They would be apples to apples in terms of the quality and durability of the materials but not in terms of design or PPP. There is more about the different ways that one mattress can “match” another mattress in post #9 here but every layer and component in a mattress will have some effect on all the other layers and components in a mattress and on the mattress “as a whole” so every difference in any of the layers and components between two mattresses will have some effect on how they compare in terms of PPP (for better or for worse). While how big the difference would be can also depend on where someone is in the range between “I can sleep on anything” and “princess and the pea” … in many cases the effect of even seemingly smaller changes (such as changing the thickness of a layer by only an inch) can be very surprising. Depending on the overall design of a mattress and all the other specs that can affect the softness of a material besides just ILD (see post #4 here) and the sensitivity of the person … most people would be able to feel a noticeable difference between layers that were 5 ILD apart yes.
Phoenix