yes, there are differences that make the Heartfelt Beads more expensive.
First, there are different grades of silica gel. Some manufactured for sucking up liquids(kitty litter), and some for controlling humid, but not wet conditions. You can even buy silica gel that will perform differently at various humidity levels. If you go to some manufacturers sites, and some scientific type sites, you can see all the different types of gels, and how they perform. different silica gels have different size pores that determine how they perform.
Heartfelt Beads are a type of silica gel that is used in the museum industry to protect fine art. The art industry is not quite as fussy as we are. i was told by an art storage bigshot that they keep their humidity around 50%. if it sways 10 points up or down, its no big deal. If that happens to our cigars, we have a stroke. So, Heartfelt uses the better quality museum grade bead, and then to lock it in at a desired humidity level for cigars, a salt solution is added. with the salt additive, we do not have to be as precise with the amt of water that we add to our beads. the salt is what locks in the humidity level.
the museums that choose not to use the salted beads have a pretty complicated formula that they use to regulate the beads. breifly, they have to know the volume of the storage chamber,and the amount of beads that are in the chamber. then thay have a formula that determines exactly how much water to add to raise the humidity level, or how much dry beads to add to decrease the humidity level. remember, they are still using the museum grade bead, it just is not impregnated with the salt.
now, before anybody jumps down my throat, i am not saying that kitty litter wont work. i am just saying that there is a silica gel product that is designed for our use.