ΔE 22.3, loose: different enough that you should pick on purpose. Fallen Grass is a little darker, much more muted, warmer than Kabalite Green.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 22). Fallen Grass is a little darker, much more muted, warmer than Kabalite Green.
The same difference applies the other way round: Kabalite Green is a little lighter, much more saturated, 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.
See Kabalite Green on the colour wheel See Fallen Grass on the colour wheel
All matches: Kabalite Green equivalents · Fallen Grass equivalents