Gremlin Green vs Loren Forest

How close are they?

ΔE 6.8, close: similar, with a visible difference side by side. Loren Forest is a little lighter than Gremlin Green.

Can I use Loren Forest instead of Gremlin Green?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Loren Forest is a little lighter than Gremlin Green.

Can I use Gremlin Green instead of Loren Forest?

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

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.