Magenta Tone vs Red Wash

How close are they?

ΔE 37.6, loose: different enough that you should pick on purpose. Red Wash is noticeably lighter, warmer than Magenta Tone.

Can I use Red Wash instead of Magenta Tone?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 38). Red Wash is noticeably lighter, warmer than Magenta Tone.

Can I use Magenta Tone instead of Red Wash?

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