ΔE 25.1, loose: different enough that you should pick on purpose. Champagne Gold Anodized Aluminum is noticeably lighter than Runelord Brass.
Can I use Champagne Gold Anodized Aluminum instead of Runelord Brass?
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 25). Champagne Gold Anodized Aluminum is noticeably lighter than Runelord Brass.
Can I use Runelord Brass instead of Champagne Gold Anodized Aluminum?
The same difference applies the other way round: Runelord Brass is noticeably 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.