ΔE 9.6, close: similar, with a visible difference side by side. Dark Mustard Khaki is more muted, cooler than Russian Sand 7K.
Usually, if you are not matching paint already on the model. Close match (ΔE 10). Dark Mustard Khaki is more muted, cooler than Russian Sand 7K.
The same difference applies the other way round: Russian Sand 7K is more saturated, warmer.
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 Russian Sand 7K on the colour wheel See Dark Mustard Khaki on the colour wheel
All matches: Russian Sand 7K equivalents · Dark Mustard Khaki equivalents