Dark Elder Bronze vs Natural Steel

How close are they?

ΔE 28.4, loose: different enough that you should pick on purpose. Natural Steel is noticeably lighter, more muted than Dark Elder Bronze.

Can I use Natural Steel instead of Dark Elder Bronze?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 28). Natural Steel is noticeably lighter, more muted than Dark Elder Bronze.

Can I use Dark Elder Bronze instead of Natural Steel?

The same difference applies the other way round: Dark Elder Bronze is noticeably darker, more saturated.

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.