Light Gray vs Flanker Light Blue

How close are they?

ΔE 8.0, close: similar, with a visible difference side by side. Flanker Light Blue is a little lighter, more saturated, cooler than Light Gray.

Can I use Flanker Light Blue instead of Light Gray?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). Flanker Light Blue is a little lighter, more saturated, cooler than Light Gray.

Can I use Light Gray instead of Flanker Light Blue?

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