Royal Burgundy vs Sapphire Blue

How close are they?

ΔE 6.3, close: similar, with a visible difference side by side. Sapphire Blue is cooler than Royal Burgundy.

Can I use Sapphire Blue instead of Royal Burgundy?

Usually, if you are not matching paint already on the model. Close match (ΔE 6). Sapphire Blue is cooler than Royal Burgundy.

Can I use Royal Burgundy instead of Sapphire Blue?

The same difference applies the other way round: Royal Burgundy is 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.