Earth Clay vs Thondia Brown

How close are they?

ΔE 7.6, close: similar, with a visible difference side by side. Thondia Brown is a little darker, more muted than Earth Clay.

Can I use Thondia Brown instead of Earth Clay?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). Thondia Brown is a little darker, more muted than Earth Clay.

Can I use Earth Clay instead of Thondia Brown?

The same difference applies the other way round: Earth Clay is a little lighter, more saturated.

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.