PetSmart's "Top Fin" line are re-branded UPG products. United Pet Group owns many labels, and seems to acquire new ones all the time.
Tetra, Marineland, Instant Ocean, Aquarium Systems, Perfecto...
The Top Fin salt will be whichever one they can get a bulk deal on, really cheap. Top Fin stuff is never "high end" - far from it.

Notice the Top Fin salt does not list any parameters on the packing, and is referred to as "marine salt" not REEF. I'm sure it's suitable for a FOWLR or they wouldn't sell it... but with Top Fin, you get what you pay for.