The surface of a roasted bean is darker than the interior. Since the whole bean rating is the color of the surface; it will be lower than the ground rating, which also includes the less roasted interior. The ground rating tells you how dark overall the roast is; the difference between the two ratings tells you how fast the roast went (the bigger the difference, the faster the roast). In general, faster roasts at the same ground Agtron level have more intense and more widely spread flavors; longer roasts have more focused, mellower flavors.