Dark Olive Green FS-34130 vs Olive Grey

How close are they?

ΔE 6.8, close: similar, with a visible difference side by side. Olive Grey is more muted than Dark Olive Green FS-34130.

Can I use Olive Grey instead of Dark Olive Green FS-34130?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Olive Grey is more muted than Dark Olive Green FS-34130.

Can I use Dark Olive Green FS-34130 instead of Olive Grey?

The same difference applies the other way round: Dark Olive Green FS-34130 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.