Like I said, same sponge, but neo is treated. Juste the NEO goes to another stop in the manufacturing process the regular does not.
Old H3 was released in 2000, at a time where the speed glue was commonly used. So they developped it with the compatibilty of Speed glue. The organic glue expanded the pores of the sponge to improve elasticity. But that process reduced significantly the life of the rubber. And according to them, NEO improve strength and durability of the sponge. So, I now understand why pro's use NEO version. It handles the boost much better.
That is explained by DHS themselves in their handbook.
drive.google.com