Loren Forest vs Fallen Grass

How close are they?

ΔE 19.6, loose: different enough that you should pick on purpose. Fallen Grass is much more muted, cooler than Loren Forest.

Can I use Fallen Grass instead of Loren Forest?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 20). Fallen Grass is much more muted, cooler than Loren Forest.

Can I use Loren Forest instead of Fallen Grass?

The same difference applies the other way round: Loren Forest is much more saturated, 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.