Griffon Blue vs Brilliant Blue

How close are they?

ΔE 15.2, loose: different enough that you should pick on purpose. Brilliant Blue is a little lighter, much more saturated than Griffon Blue.

Can I use Brilliant Blue instead of Griffon Blue?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Brilliant Blue is a little lighter, much more saturated than Griffon Blue.

Can I use Griffon Blue instead of Brilliant Blue?

The same difference applies the other way round: Griffon Blue 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.