Ruinous Spell vs J.N. Green

How close are they?

ΔE 8.3, close: similar, with a visible difference side by side. J.N. Green is a little darker, warmer than Ruinous Spell.

Can I use J.N. Green instead of Ruinous Spell?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). J.N. Green is a little darker, warmer than Ruinous Spell.

Can I use Ruinous Spell instead of J.N. Green?

The same difference applies the other way round: Ruinous Spell 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.