ΔE 6.9, close: similar, with a visible difference side by side. Arrakis Brown is more muted than Fiendish Yellow.
Usually, if you are not matching paint already on the model. Close match (ΔE 7). Arrakis Brown is more muted than Fiendish Yellow.
The same difference applies the other way round: Fiendish Yellow is 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.
See Fiendish Yellow on the colour wheel See Arrakis Brown on the colour wheel
All matches: Fiendish Yellow equivalents · Arrakis Brown equivalents