Pure chocolate is too bitter for most people. Dark chocolate is less bitter, and comes in various percentages of cocao, combined with dairy, and sugar. Dairy is inexpensive, and dilutes the bitter cocoa nibs, and adds a creamy texture to the end product. Cocoa butter, cocoa nibs, sugar, and dried milk are combined to produce chocolate.
If you were to place a tsp. of cocoa powder in your mouth, that's the flavor of pure chocolate.
There are dairy, sugar, and nut free chocolate confectios that can be found. It takes a bit of internet searching to find them.
Like Andy said, different companies have their own recipes for their product. The cocoa beans bary in flavor, depending on growing conditions, climate, soil composition, how long the neans are fermented, and roasted, and what ingredients are added.
Coverture chocolate is made using pure cocoa butter as the only fat. When tempered, it produces a crisp snap, and melts smoothly in your mouth, with no grainy, or waxy texture.
Hope that helps answer your question.