Putrid White vs Greatcoat Green

How close are they?

ΔE 9.7, close: similar, with a visible difference side by side. Greatcoat Green is a little darker, more saturated, cooler than Putrid White.

Can I use Greatcoat Green instead of Putrid White?

Usually, if you are not matching paint already on the model. Close match (ΔE 10). Greatcoat Green is a little darker, more saturated, cooler than Putrid White.

Can I use Putrid White instead of Greatcoat Green?

The same difference applies the other way round: Putrid White is a little lighter, more muted, warmer.

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.