Here is my black pastel that I hatched out:



See how she's more BLACK than brown? Black pastels don't tend to have much brown on their base pattern. A normal (like yours) is mostly brown. The actual pattern is different too. A black pastel tends to have key holes where your normal usually has what we call alien heads because they have two holes in each piece of pattern. Another cool difference is that black pastels tend to have some pieces of their pattern that are connected. Look at my girl's tail and on the side of her neck. See how they are connected? Your normal will usually have a clear break between each piece of pattern.