ΔE 15.3, loose: different enough that you should pick on purpose. Imperial Blue is noticeably darker, cooler than Braineater Azure.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Imperial Blue is noticeably darker, cooler than Braineater Azure.
The same difference applies the other way round: Braineater Azure is noticeably lighter, 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 Braineater Azure on the colour wheel See Imperial Blue on the colour wheel
All matches: Braineater Azure equivalents · Imperial Blue equivalents