ΔE 22.1, loose: different enough that you should pick on purpose. Base Flesh is noticeably lighter, more muted, warmer than Mars Yellow.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 22). Base Flesh is noticeably lighter, more muted, warmer than Mars Yellow.
The same difference applies the other way round: Mars Yellow is noticeably darker, 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 Mars Yellow on the colour wheel See Base Flesh on the colour wheel
All matches: Mars Yellow equivalents · Base Flesh equivalents