ΔE 30.2, loose: different enough that you should pick on purpose. Hydra Turquoise is a little darker, much more saturated than Blue Steel.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 30). Hydra Turquoise is a little darker, much more saturated than Blue Steel.
The same difference applies the other way round: Blue Steel is a little lighter, much more muted.
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 Blue Steel on the colour wheel See Hydra Turquoise on the colour wheel
All matches: Blue Steel equivalents · Hydra Turquoise equivalents