ΔE 27.6, loose: different enough that you should pick on purpose. Hydra Turquoise is noticeably lighter, more saturated, cooler than Sparkling Amethyst.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 28). Hydra Turquoise is noticeably lighter, more saturated, cooler than Sparkling Amethyst.
The same difference applies the other way round: Sparkling Amethyst is noticeably darker, 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 Sparkling Amethyst on the colour wheel See Hydra Turquoise on the colour wheel
All matches: Sparkling Amethyst equivalents · Hydra Turquoise equivalents