ΔE 7.9, close: similar, with a visible difference side by side. Ochre Brown is a little darker, more muted, warmer than RAF Middle Stone.
Usually, if you are not matching paint already on the model. Close match (ΔE 8). Ochre Brown is a little darker, more muted, warmer than RAF Middle Stone.
The same difference applies the other way round: RAF Middle Stone is a little lighter, more saturated, 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 RAF Middle Stone on the colour wheel See Ochre Brown on the colour wheel
All matches: RAF Middle Stone equivalents · Ochre Brown equivalents