Russian Uniform Lights vs Dark Yellow

How close are they?

ΔE 9.5, close: similar, with a visible difference side by side. Dark Yellow is a little lighter than Russian Uniform Lights.

Can I use Dark Yellow instead of Russian Uniform Lights?

Usually, if you are not matching paint already on the model. Close match (ΔE 9). Dark Yellow is a little lighter than Russian Uniform Lights.

Can I use Russian Uniform Lights instead of Dark Yellow?

The same difference applies the other way round: Russian Uniform Lights is a little darker.

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.