Teclis Blue vs Ghost Blue

How close are they?

ΔE 19.9, loose: different enough that you should pick on purpose. Ghost Blue is a little darker, warmer than Teclis Blue.

Can I use Ghost Blue instead of Teclis Blue?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 20). Ghost Blue is a little darker, warmer than Teclis Blue.

Can I use Teclis Blue instead of Ghost Blue?

The same difference applies the other way round: Teclis Blue is a little lighter, 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.