ΔE 19.2, loose: different enough that you should pick on purpose. Brutal Brown is noticeably darker, warmer than Moonstone Skin.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Brutal Brown is noticeably darker, warmer than Moonstone Skin.
The same difference applies the other way round: Moonstone Skin is noticeably lighter, 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 Brutal Brown on the colour wheel
All matches: Moonstone Skin equivalents · Brutal Brown equivalents