These four materials all fall into the category of super austenitic stainless steels, designed to withstand extreme corrosive environments where even 316L is inadequate. In simple terms: N08904 is the "veteran champion in acid resistance", S31254 is the "benchmark of six-molybdenum grade", N08926 is the "upgraded and enhanced version", and N08367 is the "nuclear-grade powerhouse". Their core differences lie in their Pitting Resistance Equivalent Number (PREN) and applicable media, with detailed comparisons as follows: