Olive Drab vs Zinc-Chromate Type I FS34151

How close are they?

ΔE 8.0, close: similar, with a visible difference side by side. Zinc-Chromate Type I FS34151 is a little darker, warmer than Olive Drab.

Can I use Zinc-Chromate Type I FS34151 instead of Olive Drab?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). Zinc-Chromate Type I FS34151 is a little darker, warmer than Olive Drab.

Can I use Olive Drab instead of Zinc-Chromate Type I FS34151?

The same difference applies the other way round: Olive Drab is a little lighter, 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.