ΔE 22.5, loose: different enough that you should pick on purpose. Moot Green is a little darker, much more saturated, cooler than Grass Green.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 23). Moot Green is a little darker, much more saturated, cooler than Grass Green.
The same difference applies the other way round: Grass Green is a little lighter, much more muted, 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.
See Grass Green on the colour wheel See Moot Green on the colour wheel
All matches: Grass Green equivalents · Moot Green equivalents