Deep Azure vs Emerald Scream

How close are they?

ΔE 22.2, loose: different enough that you should pick on purpose. Emerald Scream is a little lighter, more saturated, warmer than Deep Azure.

Can I use Emerald Scream instead of Deep Azure?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 22). Emerald Scream is a little lighter, more saturated, warmer than Deep Azure.

Can I use Deep Azure instead of Emerald Scream?

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