ΔE 9.0, close: similar, with a visible difference side by side. Buff is more saturated, warmer than Dark Yellow.
Usually, if you are not matching paint already on the model. Close match (ΔE 9). Buff is more saturated, warmer than Dark Yellow.
The same difference applies the other way round: Dark Yellow is more muted, 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 Dark Yellow on the colour wheel See Buff on the colour wheel
All matches: Dark Yellow equivalents · Buff equivalents