ΔE 14.4, fair: the same colour family, but not a straight swap. Alien Purple is a little lighter, warmer than Thunder Blue.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 14). Alien Purple is a little lighter, warmer than Thunder Blue.
The same difference applies the other way round: Thunder Blue is a little darker, 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 Thunder Blue on the colour wheel See Alien Purple on the colour wheel
All matches: Thunder Blue equivalents · Alien Purple equivalents