ΔE 13.1, fair: the same colour family, but not a straight swap. Dawnstone is noticeably darker than Iron Man.
Can I use Dawnstone instead of Iron Man?
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 13). Dawnstone is noticeably darker than Iron Man.
Can I use Iron Man instead of Dawnstone?
The same difference applies the other way round: Iron Man is noticeably lighter.
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.