Elf Green vs Thornwood Green

How close are they?

ΔE 9.7, close: similar, with a visible difference side by side. Thornwood Green is a little lighter, warmer than Elf Green.

Can I use Thornwood Green instead of Elf Green?

Usually, if you are not matching paint already on the model. Close match (ΔE 10). Thornwood Green is a little lighter, warmer than Elf Green.

Can I use Elf Green instead of Thornwood Green?

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