Light Soviet Khaki vs Dark Yellow

How close are they?

ΔE 7.8, close: similar, with a visible difference side by side. Dark Yellow is a little darker, more saturated than Light Soviet Khaki.

Can I use Dark Yellow instead of Light Soviet Khaki?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). Dark Yellow is a little darker, more saturated than Light Soviet Khaki.

Can I use Light Soviet Khaki instead of Dark Yellow?

The same difference applies the other way round: Light Soviet Khaki is a little lighter, more muted.

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.