ΔE 10.3, fair: the same colour family, but not a straight swap. Red Ink is a little darker, more saturated than Camo Brown. They are different kinds of paint: Army Painter Camo Brown is an opaque base/layer paint and Reaper Red 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 10). Red Ink is a little darker, more saturated than Camo Brown. They are different kinds of paint.
The same difference applies the other way round: Camo Brown is a little lighter, more muted.
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 Camo Brown on the colour wheel See Red Ink on the colour wheel
All matches: Camo Brown equivalents · Red Ink equivalents