ΔE 11.4, fair: the same colour family, but not a straight swap. Mahogany Ink is cooler than Steel Legion Drab. They are different kinds of paint: Citadel Steel Legion Drab is an opaque base/layer paint and Vallejo Mahogany Ink is an ink, glaze or transparent 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 11). Mahogany Ink is cooler than Steel Legion Drab. They are different kinds of paint.
The same difference applies the other way round: Steel Legion Drab is 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 Steel Legion Drab on the colour wheel See Mahogany Ink on the colour wheel
All matches: Steel Legion Drab equivalents · Mahogany Ink equivalents