Augur Blue vs Gigawatt Blue

How close are they?

ΔE 20.8, loose: different enough that you should pick on purpose. Gigawatt Blue is a little darker, much more saturated, cooler than Augur Blue.

Can I use Gigawatt Blue instead of Augur Blue?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 21). Gigawatt Blue is a little darker, much more saturated, cooler than Augur Blue.

Can I use Augur Blue instead of Gigawatt Blue?

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