Do designers use the same RAM (Radar Absorbing Material) coating across the length and breadth of a fighter aircraft? I was looking at this image:


Image from Wikipedia

and couldn't help notice that the RAM coating looks different on the vertical/horizontal stabilizers and wings compared to the fuselage. 

Given the fact that there are different types of RAM, such as iron ball paint absorber, foam absorber, etc... Are different types of RAMs being used in order to achieve stealth?
According to this article and this book, they use a greater amount of wide-band structural RAM on the wing's edges, whereas they use a ceramic-matrix RAM on the exhaust nozzles. Not only is that the case, but the actual edges have proprietary material designed to be stronger, and have a different radar signature. Although, what you're seeing is probably a combination of the paint job as well as the material, considering the F-22's stealth is not only an aspect of radar, but also visibility. 

Most of the stealth of the F-22 comes from the physical shape of the F-22, and reducing its radar cross-section. There are also specialized materials that assist in obscuring its infrared signature. The topcoat, a type of paint, assists in reducing the infrared signature, especially.