Ogre Green vs Loren Forest

How close are they?

ΔE 9.4, close: similar, with a visible difference side by side. Loren Forest is a little lighter, more saturated than Ogre Green.

Can I use Loren Forest instead of Ogre Green?

Usually, if you are not matching paint already on the model. Close match (ΔE 9). Loren Forest is a little lighter, more saturated than Ogre Green.

Can I use Ogre Green instead of Loren Forest?

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

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.