Wraithbone vs Vampire Fang

How close are they?

ΔE 6.4, close: similar, with a visible difference side by side. Vampire Fang is a little darker, warmer than Wraithbone.

Can I use Vampire Fang instead of Wraithbone?

Usually, if you are not matching paint already on the model. Close match (ΔE 6). Vampire Fang is a little darker, warmer than Wraithbone.

Can I use Wraithbone instead of Vampire Fang?

The same difference applies the other way round: Wraithbone is a little lighter, cooler.

ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.