ΔE 21.4, loose: different enough that you should pick on purpose. Ivory Tusk is a little darker, much more muted than Mossy Green.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 21). Ivory Tusk is a little darker, much more muted than Mossy Green.
The same difference applies the other way round: Mossy Green is a little lighter, much more saturated.
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 Mossy Green on the colour wheel See Ivory Tusk on the colour wheel
All matches: Mossy Green equivalents · Ivory Tusk equivalents