Gordian Knot vs Aged Metal

How close are they?

ΔE 19.7, loose: different enough that you should pick on purpose. Aged Metal is noticeably darker, more muted, warmer than Gordian Knot.

Can I use Aged Metal instead of Gordian Knot?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 20). Aged Metal is noticeably darker, more muted, warmer than Gordian Knot.

Can I use Gordian Knot instead of Aged Metal?

The same difference applies the other way round: Gordian Knot is noticeably lighter, more saturated, cooler.

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.