Light Ghost Gray vs Sunrise Blue

How close are they?

ΔE 21.3, loose: different enough that you should pick on purpose. Sunrise Blue is noticeably lighter, more saturated, warmer than Light Ghost Gray.

Can I use Sunrise Blue instead of Light Ghost Gray?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 21). Sunrise Blue is noticeably lighter, more saturated, warmer than Light Ghost Gray.

Can I use Light Ghost Gray instead of Sunrise Blue?

The same difference applies the other way round: Light Ghost Gray is noticeably 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.