ΔE 7.8, close: similar, with a visible difference side by side. Interior Green is a little lighter, more muted than Helmet Brown.
Usually, if you are not matching paint already on the model. Close match (ΔE 8). Interior Green is a little lighter, more muted than Helmet Brown.
The same difference applies the other way round: Helmet Brown is a little darker, more saturated.
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 Helmet Brown on the colour wheel See Interior Green on the colour wheel
All matches: Helmet Brown equivalents · Interior Green equivalents