ΔE 6.6, close: similar, with a visible difference side by side. Our swatches for the two are almost the same. They are different kinds of paint: Citadel Mephiston Red is an opaque base/layer paint and Vallejo Ink Red 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 7). The swatches are almost the same. They are different kinds of paint.
The same difference applies the other way round.
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 Mephiston Red on the colour wheel See Ink Red on the colour wheel
All matches: Mephiston Red equivalents · Ink Red equivalents