WWI French Brown vs Thondia Brown

How close are they?

ΔE 9.6, close: similar, with a visible difference side by side. Thondia Brown is a little lighter, warmer than WWI French Brown.

Can I use Thondia Brown instead of WWI French Brown?

Usually, if you are not matching paint already on the model. Close match (ΔE 10). Thondia Brown is a little lighter, warmer than WWI French Brown.

Can I use WWI French Brown instead of Thondia Brown?

The same difference applies the other way round: WWI French Brown is a little darker, 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.