Grimdark Shadow vs Andalusian Earth

How close are they?

ΔE 14.7, fair: the same colour family, but not a straight swap. Andalusian Earth is noticeably lighter than Grimdark Shadow.

Can I use Andalusian Earth instead of Grimdark Shadow?

Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 15). Andalusian Earth is noticeably lighter than Grimdark Shadow.

Can I use Grimdark Shadow instead of Andalusian Earth?

The same difference applies the other way round: Grimdark Shadow is noticeably darker.

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.