Hi Jeremy,
All of them are different forms of Talalay latex.
The “Natural” is made with a blend of 30% natural and 70% synthetic rubber.
The “All Natural” is made with natural rubber only and doesn’t use any synthetic rubber in the formula. Post #2 here has more about the difference between 100% natural and blended talalay latex.
Active Fusion is what Latex International calls Talalay GL (and used to be called Celsion) and is blended Talalay with some phase change gel microparticles added to the formula to help with temperature regulation. It comes in a fast and slow response version (NOTE: they are no longer making the slow response version). While Talalay latex is already among the most breathable and temperature regulating of all the foam materials … the phase change gel can add a slight benefit for those who feel they may need it (see post #2 here).
The fast response is very similar to the blended Talalay in a similar ILD.
The slow response is also a blended Talalay but is made to have some of the delayed response and “feel” of memory foam and if you compress it the material leaves a hand print for a few seconds. (NOTE: this has now been discontinued).
Which one would be more comfortable would be a completely subjective choice.
Phoenix