ΔE 19.7, loose: different enough that you should pick on purpose. Tyran Blue is more saturated, cooler than Matt Purple. They are different kinds of paint: AMMO by Mig Matt Purple is an ink, glaze or transparent paint and Citadel Tyran Blue is a wash/shade, so they won’t behave the same on the model even where the colour is close.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 20). Tyran Blue is more saturated, cooler than Matt Purple. They are different kinds of paint.
The same difference applies the other way round: Matt Purple is more muted, 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 Matt Purple on the colour wheel See Tyran Blue on the colour wheel
All matches: Matt Purple equivalents · Tyran Blue equivalents