Cobalt Green vs Deep Green

How close are they?

ΔE 7.5, close: similar, with a visible difference side by side. Deep Green is a little darker, warmer than Cobalt Green.

Can I use Deep Green instead of Cobalt Green?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Deep Green is a little darker, warmer than Cobalt Green.

Can I use Cobalt Green instead of Deep Green?

The same difference applies the other way round: Cobalt Green 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.