ΔE 21.7, loose: different enough that you should pick on purpose. Earth Brown is a little darker, much more muted, warmer than Moonstone Skin.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 22). Earth Brown is a little darker, much more muted, warmer than Moonstone Skin.
The same difference applies the other way round: Moonstone Skin 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 Moonstone Skin on the colour wheel See Earth Brown on the colour wheel
All matches: Moonstone Skin equivalents · Earth Brown equivalents