ΔE 40.1, loose: different enough that you should pick on purpose. Ink Dark Turquoise is noticeably darker, much more muted, warmer than Inktense Cyan.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 40). Ink Dark Turquoise is noticeably darker, much more muted, warmer than Inktense Cyan.
The same difference applies the other way round: Inktense Cyan is noticeably lighter, 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.
See Inktense Cyan on the colour wheel See Ink Dark Turquoise on the colour wheel
All matches: Inktense Cyan equivalents · Ink Dark Turquoise equivalents