The head displayed on top is shinier due to the fact that it is brand new. If you look closely, you will always notice the blue bristles near the top of the head that extend all the way to the brushing surface. This head also has fresh bristles intact in a tight bunch.
The head on the bottom has lost its shine due to deposits accumulated from heavy use over time. The head as a whole has a yellow appearance. This head’s blue bristles have also lost their color, which have faded and is also a key indicator that this head requires replacement.