Okay I hope this isn’t a dumb question, but its been bothering me for a long time now, I just don’t understand what the difference is between snuff labled black or dark and snuff that is labled brown. Particularly I am looking at my viking snuffs because that is the only thing in the name, viking dark or viking brown. Both are excellent, I think I like the dark better but I have not really given the brown one enough of a try. My assimption is that the snuff undergoes a different process, but I have no futher guess as to what that process is; a simple verson of the answer is all I need if possible.
I don’t think this is a dumb question at all…I’ve assumed dark & brown were two different types of tobacco…we’ll see what others say. 
Well, the obvious answer is that one is colored brown and one is colored black, but I assume that’s not what you are asking. They do undergo a different curing process, and as a result have different colors as well as flavors/scents. In the case of the Viking snuffs, the dark is finer ground than the brown. Viking Brown is a variety of a distinct genre of snuff, Kendal Brown, which is typically moist, fairly course, and typically enhanced with a citrusy type scent.
The answer is the maillard reaction. The darkening of organic matter when exposed to heat. In this case the heat generated by fermentation. The black has been exposed longer or to higher temperatures. Most dark snuffs are darker because of this but not all such as the snuff that is darkened by the addition of coffee beans.