ΔE 9.7, close: similar, with a visible difference side by side. Payne's Gray is a little darker, warmer than Iron Wolf. They are different kinds of paint: Army Painter Iron Wolf is an opaque base/layer paint and Golden Payne's Gray is an ink, glaze or transparent paint, so they won’t behave the same on the model even where the colour is close.
Usually, if you are not matching paint already on the model. Close match (ΔE 10). Payne's Gray is a little darker, warmer than Iron Wolf. They are different kinds of paint.
The same difference applies the other way round: Iron Wolf is a little lighter, 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 Iron Wolf on the colour wheel See Payne's Gray on the colour wheel
All matches: Iron Wolf equivalents · Payne's Gray equivalents