ΔE 15.4, loose: different enough that you should pick on purpose. Rusty Metal is much more saturated, warmer than Aged Pewter.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Rusty Metal is much more saturated, warmer than Aged Pewter.
The same difference applies the other way round: Aged Pewter is much more muted, 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.
See Aged Pewter on the colour wheel See Rusty Metal on the colour wheel
All matches: Aged Pewter equivalents · Rusty Metal equivalents