ΔE 54.3, loose: different enough that you should pick on purpose. Smoke Grey Wash is noticeably lighter, much more muted than Poxwalker.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 54). Smoke Grey Wash is noticeably lighter, much more muted than Poxwalker.
The same difference applies the other way round: Poxwalker is noticeably darker, much more saturated.
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 Poxwalker on the colour wheel See Smoke Grey Wash on the colour wheel
All matches: Poxwalker equivalents · Smoke Grey Wash equivalents