Paprika can be made from several different varietals of the chile pepper family Capsicum annuum, though the different peppers all tend to be of the relatively long, tapered kind with thinner flesh. Fat, thick-fleshed sweet peppers, like a standard Bell pepper that you’ll find in your average grocery store, often don’t dry well enough to make a ground product and are prone to mold. They are valued for their bright red color as much as--or even more than--their flavor. The American Spice Trade Association, or ASTA, came up with a scale to measure paprika's color. The ASTA score goes from 50-180; 85 is a standard-grade color value. As the numbers go up, the color of the paprika is more saturated and vibrant.

If you wonder whether you can substitute one for the other, the answer is yes. You would use a lot less red chili powder, even if it is of the milder variety, than you would paprika. In fact, the best way to go about this is add it slowly and in small amounts, till you get the heat factor that you want. In a pinch, you can use paprika instead of red chili powder as well, though you may not get the color that you want and the flavor may be different.