Thondia Brown vs Burnt Umber

How close are they?

ΔE 8.6, close: similar, with a visible difference side by side. Burnt Umber is a little darker, more muted than Thondia Brown.

Can I use Burnt Umber instead of Thondia Brown?

Usually, if you are not matching paint already on the model. Close match (ΔE 9). Burnt Umber is a little darker, more muted than Thondia Brown.

Can I use Thondia Brown instead of Burnt Umber?

The same difference applies the other way round: Thondia Brown 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.