Gryph-Charger Grey vs Bright Slate Grey

How close are they?

ΔE 6.4, close: similar, with a visible difference side by side. Bright Slate Grey is a little lighter than Gryph-Charger Grey.

Can I use Bright Slate Grey instead of Gryph-Charger Grey?

Usually, if you are not matching paint already on the model. Close match (ΔE 6). Bright Slate Grey is a little lighter than Gryph-Charger Grey.

Can I use Gryph-Charger Grey instead of Bright Slate Grey?

The same difference applies the other way round: Gryph-Charger Grey is a little darker.

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.