Dark Olive Drab vs Dark Soviet Khaki

How close are they?

ΔE 6.3, close: similar, with a visible difference side by side. Dark Soviet Khaki is more muted than Dark Olive Drab.

Can I use Dark Soviet Khaki instead of Dark Olive Drab?

Usually, if you are not matching paint already on the model. Close match (ΔE 6). Dark Soviet Khaki is more muted than Dark Olive Drab.

Can I use Dark Olive Drab instead of Dark Soviet Khaki?

The same difference applies the other way round: Dark Olive Drab is more saturated.

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.