ΔE 15.4, loose: different enough that you should pick on purpose. Grayish Blue FS35237 is a little darker, much more muted, cooler than Hydra Turquoise.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Grayish Blue FS35237 is a little darker, much more muted, cooler than Hydra Turquoise.
The same difference applies the other way round: Hydra Turquoise is a little lighter, much more saturated, 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 Hydra Turquoise on the colour wheel See Grayish Blue FS35237 on the colour wheel
All matches: Hydra Turquoise equivalents · Grayish Blue FS35237 equivalents