Magenta Tone vs Flesh Wash

How close are they?

ΔE 48.5, loose: different enough that you should pick on purpose. Flesh Wash is noticeably lighter, much more muted, warmer than Magenta Tone.

Can I use Flesh Wash instead of Magenta Tone?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 49). Flesh Wash is noticeably lighter, much more muted, warmer than Magenta Tone.

Can I use Magenta Tone instead of Flesh Wash?

The same difference applies the other way round: Magenta Tone is noticeably darker, 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.