Green Tone vs Necrosis Green Wash

How close are they?

ΔE 39.1, loose: different enough that you should pick on purpose. Necrosis Green Wash is noticeably lighter, much more muted, warmer than Green Tone.

Can I use Necrosis Green Wash instead of Green Tone?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 39). Necrosis Green Wash is noticeably lighter, much more muted, warmer than Green Tone.

Can I use Green Tone instead of Necrosis Green Wash?

The same difference applies the other way round: Green 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.