Cardinal Purple vs Doombull Brown

How close are they?

ΔE 7.5, close: similar, with a visible difference side by side. Doombull Brown is more saturated than Cardinal Purple.

Can I use Doombull Brown instead of Cardinal Purple?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Doombull Brown is more saturated than Cardinal Purple.

Can I use Cardinal Purple instead of Doombull Brown?

The same difference applies the other way round: Cardinal Purple is more muted.

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.