Turquoise vs Baharroth Blue

How close are they?

ΔE 19.8, loose: different enough that you should pick on purpose. Baharroth Blue is noticeably darker, more saturated than Turquoise.

Can I use Baharroth Blue instead of Turquoise?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 20). Baharroth Blue is noticeably darker, more saturated than Turquoise.

Can I use Turquoise instead of Baharroth Blue?

The same difference applies the other way round: Turquoise is noticeably lighter, 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.