ΔE 10.6, fair: the same colour family, but not a straight swap. Orange Tone is more saturated than Mushroom Brown. They are different kinds of paint: AMMO by Mig Mushroom Brown is an opaque base/layer paint and Army Painter Orange Tone is a wash/shade, 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). Orange Tone is more saturated than Mushroom Brown. They are different kinds of paint.
The same difference applies the other way round: Mushroom Brown is 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 Mushroom Brown on the colour wheel See Orange Tone on the colour wheel
All matches: Mushroom Brown equivalents · Orange Tone equivalents