Wraihtbone is a bit warmer, white scar is supposed to be white (not sure if you bought the old one or the new one) but yes as MrFox said drybrushing some real white paint helps a bit. If you want even more definition and contrast, before you drybrush, you can do a bit of shading with a shade too. Or oil wash after you painted the whole model. I found Grey Seer to be the closest to what I want in underlaying color and has the best coverage btw