Russian Green Uniform vs Ruinous Spell

How close are they?

ΔE 9.2, close: similar, with a visible difference side by side. Ruinous Spell is a little lighter, more saturated, cooler than Russian Green Uniform.

Can I use Ruinous Spell instead of Russian Green Uniform?

Usually, if you are not matching paint already on the model. Close match (ΔE 9). Ruinous Spell is a little lighter, more saturated, cooler than Russian Green Uniform.

Can I use Russian Green Uniform instead of Ruinous Spell?

The same difference applies the other way round: Russian Green Uniform is a little darker, 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.