Pylar Glacier vs Ancestral Blue

How close are they?

ΔE 16.4, loose: different enough that you should pick on purpose. Ancestral Blue is a little lighter, more saturated, cooler than Pylar Glacier.

Can I use Ancestral Blue instead of Pylar Glacier?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Ancestral Blue is a little lighter, more saturated, cooler than Pylar Glacier.

Can I use Pylar Glacier instead of Ancestral Blue?

The same difference applies the other way round: Pylar Glacier is a little darker, more muted, 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.