ΔE 9.4, close: similar, with a visible difference side by side. Iron Warriors is a little darker, more saturated than Steel.
Usually, if you are not matching paint already on the model. Close match (ΔE 9). Iron Warriors is a little darker, more saturated than Steel.
The same difference applies the other way round: Steel is a little lighter, more muted.
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.
See Steel on the colour wheel See Iron Warriors on the colour wheel
All matches: Steel equivalents · Iron Warriors equivalents