ΔE 9.3, close: similar, with a visible difference side by side. Ink Yellow is warmer than Fiendish Yellow. They are different kinds of paint: Army Painter Fiendish Yellow is an opaque base/layer paint and Vallejo Ink Yellow is an ink, glaze or transparent paint, so they won’t behave the same on the model even where the colour is close.
Usually, if you are not matching paint already on the model. Close match (ΔE 9). Ink Yellow is warmer than Fiendish Yellow. They are different kinds of paint.
The same difference applies the other way round: Fiendish Yellow is 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.
See Fiendish Yellow on the colour wheel See Ink Yellow on the colour wheel
All matches: Fiendish Yellow equivalents · Ink Yellow equivalents