ΔE 12.1, fair: the same colour family, but not a straight swap. Raw Sienna is noticeably lighter than Hardened Leather. They are different kinds of paint: Army Painter Hardened Leather is a one-coat contrast-style paint and Golden Raw Sienna is an opaque base/layer paint, so they won’t behave the same on the model even where the colour is close.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Raw Sienna is noticeably lighter than Hardened Leather. They are different kinds of paint.
The same difference applies the other way round: Hardened Leather is noticeably darker.
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 Hardened Leather on the colour wheel See Raw Sienna on the colour wheel
All matches: Hardened Leather equivalents · Raw Sienna equivalents