Sky Gray vs Sunrise Blue

How close are they?

ΔE 20.4, loose: different enough that you should pick on purpose. Sunrise Blue is a little lighter, much more saturated than Sky Gray.

Can I use Sunrise Blue instead of Sky Gray?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 20). Sunrise Blue is a little lighter, much more saturated than Sky Gray.

Can I use Sky Gray instead of Sunrise Blue?

The same difference applies the other way round: Sky Gray is a little darker, much 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.