ΔE 6.7, close: similar, with a visible difference side by side. Brown RLM26 is a little lighter, warmer than Red Brown.
Usually, if you are not matching paint already on the model. Close match (ΔE 7). Brown RLM26 is a little lighter, warmer than Red Brown.
The same difference applies the other way round: Red Brown is a little darker, cooler.
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 Red Brown on the colour wheel See Brown RLM26 on the colour wheel
All matches: Red Brown equivalents · Brown RLM26 equivalents