Dryad Brown vs Dread Red

How close are they?

ΔE 8.6, close: similar, with a visible difference side by side. Dread Red is a little lighter, cooler than Dryad Brown.

Can I use Dread Red instead of Dryad Brown?

Usually, if you are not matching paint already on the model. Close match (ΔE 9). Dread Red is a little lighter, cooler than Dryad Brown.

Can I use Dryad Brown instead of Dread Red?

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