Retributor Armour vs Runic Gold

How close are they?

ΔE 15.3, loose: different enough that you should pick on purpose. Runic Gold is noticeably darker, cooler than Retributor Armour.

Can I use Runic Gold instead of Retributor Armour?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Runic Gold is noticeably darker, cooler than Retributor Armour.

Can I use Retributor Armour instead of Runic Gold?

The same difference applies the other way round: Retributor Armour is noticeably lighter, 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.