KB has chemicals as a binder and additives creating effectively an artificial smoke taste. Yes there is plenty of real smoke flavor in KB because it is still predominately wood charcoal but the burning of artificial ingredients onto your meat is going to create flavor too.
Stubbs does not have this because it is purely wood derived charcoal and corn starch as a binder. The grease fog flavor tastes more like a pure charcoal taste.
For most people, this taste difference is not going to be a big deal. And both brands create fantastic food.
I myself, try to eliminate as many artificial ingredients from my diet. I was a KB user on the PBC for over a year of owning the PBC. I was afraid to try others because Noah's instructions have been full proof for me. But after learning about Stubbs and Royal Oak being all natural, and trying both, Stubbs is now my new go to charcoal.
I liken it to ice cream. I used to LOVE Blue Bell Ice Cream. Even before their recall I quit eating it because it is predominantly artificial ingredients used to create color, taste, and texture. Switching to an all natural ice cream has a more subtle yet rich taste. It may not taste as sweet, but you don't need it to be as sweet because the sweetness is all natural. The artificial flavor from Blue Bell creates a taste so sweet it tricks your brain into wanting more than you should have. A creamier natural ice cream (due to better milk/cream and pure cane sugar) feels more indulgent causing you to want less.
So to me, it makes me wonder if the chemicals used create an artificial smoke taste that makes a person addicted to the KB charcoal.