Senshi Skin vs Morghast Bone

How close are they?

ΔE 6.9, close: similar, with a visible difference side by side. Morghast Bone is a little darker, cooler than Senshi Skin.

Can I use Morghast Bone instead of Senshi Skin?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Morghast Bone is a little darker, cooler than Senshi Skin.

Can I use Senshi Skin instead of Morghast Bone?

The same difference applies the other way round: Senshi Skin is a little lighter, warmer.

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.