Calcium hypochlorite
Along with its variations are indeed the same "dry" chlorine bleach found in pool disinfecting chemicals. You also find it in scouring powders like Comet, Ajax and others "with bleach". Commercial laundries have long used dry chlorine bleach for several reasons ranging from longer shelf life/stability than liquid to being a bit more powerful.
https://en.wikipedia.org/wiki/Calcium_hypochlorite
Various brands have long sold dry chlorine bleach in vend box sizes for sale/use in laundromats.
For a chlorine based product to have an EPA registry number and thus provide disinfection it must contain a certain percentage of that chemical. Clorox and other brands have long weakened their bottled liquid bleaches so that not all products are disinfectants. Most consumers either are ignorant of this and or just do not care. You often have to search through several shelves of chlorine bleaches at a supermarket to find one that is an EPA registered disinfectant.
My theory is Clorox and others have weakened their chlorine bleaches to lessen the aggressive nature. Milder chlorine bleach will still whiten and remove stains, but perhaps not at the expense of destroying fabric and or totally ruining all colors.
Lack of an EPA number may also mean the bleach product does not have the chlorine power to deal with mold and mildew. In both cases the control of mold/mildew and disinfecting if that is what is wanted best to read the label/directions. If the container makes no mention of either function then another choice may prove wiser.
Have seen both these bleach pods and crystals for some time now but am not interested.
For one do not need nor use chlorine bleach with my laundry. Both my Miele and Oko-Lavamat are capable of boil or near wash temperatures. Laundering at or near 200F with a good dose of oxygen bleach is all one requires.
Second would be *VERY* leary of using either in a front loader or any machine where undiluted product stands a remote chance of coming into contact with washing.