I saw something similar last year from BioGuard. They had their usual 6lbs container of Stabilizer-100 (100% CYA) and another bottle of Saltscapes SunShield Stabilizer for salt water pools....also 100% CYA but about $10 more....I guess the nicer looking bottle is worth the extra money so it's easier on the eye for those poor fellows working the recycle garbage truck
Just about ever pool chemical brand has a "saltwater" version of their chemicals. They are almost always exactly the same except in smaller containers and priced higher. Reminds me of the individually wrapped "microwavable" potatoes.