ΔE 10.8, fair: the same colour family, but not a straight swap. Altdorf Guard Blue is cooler than Purple People Eater.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Altdorf Guard Blue is cooler than Purple People Eater.
The same difference applies the other way round: Purple People Eater is warmer.
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 Purple People Eater on the colour wheel See Altdorf Guard Blue on the colour wheel
All matches: Purple People Eater equivalents · Altdorf Guard Blue equivalents