ΔE 27.3, loose: different enough that you should pick on purpose. Ultramarine Blue is noticeably darker, more saturated, warmer than Psychotic Illusions.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 27). Ultramarine Blue is noticeably darker, more saturated, warmer than Psychotic Illusions.
The same difference applies the other way round: Psychotic Illusions is noticeably lighter, more muted, 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 Psychotic Illusions on the colour wheel See Ultramarine Blue on the colour wheel
All matches: Psychotic Illusions equivalents · Ultramarine Blue equivalents