ΔE 17.1, loose: different enough that you should pick on purpose. Amethyst Purple is a little darker, more saturated, cooler than Lunar Eclipse.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Amethyst Purple is a little darker, more saturated, cooler than Lunar Eclipse.
The same difference applies the other way round: Lunar Eclipse is a little lighter, more muted, warmer.
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 Lunar Eclipse on the colour wheel See Amethyst Purple on the colour wheel
All matches: Lunar Eclipse equivalents · Amethyst Purple equivalents