ΔE 12.1, fair: the same colour family, but not a straight swap. Toxic Boils is a little darker, more saturated, cooler than Matt Natural Flesh. They are different kinds of paint: AMMO by Mig Matt Natural Flesh is an ink, glaze or transparent paint and Army Painter Toxic Boils is an opaque base/layer paint, so they won’t behave the same on the model even where the colour is close.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Toxic Boils is a little darker, more saturated, cooler than Matt Natural Flesh. They are different kinds of paint.
The same difference applies the other way round: Matt Natural Flesh is a little lighter, 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 Natural Flesh on the colour wheel See Toxic Boils on the colour wheel
All matches: Matt Natural Flesh equivalents · Toxic Boils equivalents