Hi hweywannaplay,
Welcome to the Mattress Forum! 
Here is some information about polyurethane foam here and here. In the simplest version, polyurethane foam (polyfoam) is isocyanate, polyol and water mixed, foamed and cured.
Latex in general is the most durable of all the foam materials (latex foam, memory foam, polyfoam) regardless of whether it is Dunlop or Talalay or is made from natural rubber, synthetic rubber, or a blend of both. There is more about the different types and blends of latex in post #6 here but the choice between different types and blends of latex is more of a preference and budget choice than a “better/worse” choice.
I know you didn’t ask about memory foam, but latex and memory foam are very different materials with very different properties. There is more about some of the differences between memory foam and latex in post #2 here.
Styrene Butadiene (SBR) is basically synthetic latex.You can read the Wikipedia description here.
The Simbatex layer on the top of the Simba mattress is a layer of synthetic (SBR) latex foam. I don’t have any other information about the product. Perhaps there is a member on the forum with more familiarity about the Simba mattress that can be of assistance, as the Simba website provides very little meaningful information about the specifics of the layers in their mattress.
Phoenix