ΔE 8.7, close: similar, with a visible difference side by side. Kislev Flesh is more saturated, cooler than Matt Sepia. They are different kinds of paint: AMMO by Mig Matt Sepia is an ink, glaze or transparent paint and Citadel Kislev Flesh is an opaque base/layer 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). Kislev Flesh is more saturated, cooler than Matt Sepia. They are different kinds of paint.
The same difference applies the other way round: Matt Sepia is more muted, 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.
See Matt Sepia on the colour wheel See Kislev Flesh on the colour wheel
All matches: Matt Sepia equivalents · Kislev Flesh equivalents