ΔE 19.2, loose: different enough that you should pick on purpose. Light Moss Green is noticeably darker, more muted, cooler than Greatcoat Green.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Light Moss Green is noticeably darker, more muted, cooler than Greatcoat Green.
The same difference applies the other way round: Greatcoat Green is noticeably lighter, 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.
See Greatcoat Green on the colour wheel See Light Moss Green on the colour wheel
All matches: Greatcoat Green equivalents · Light Moss Green equivalents