ΔE 15.7, loose: different enough that you should pick on purpose. Aged Pewter is a little lighter, more saturated than Steel.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Aged Pewter is a little lighter, more saturated than Steel.
The same difference applies the other way round: Steel is a little darker, 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 Aged Pewter on the colour wheel
All matches: Steel equivalents · Aged Pewter equivalents