ΔE 19.0, loose: different enough that you should pick on purpose. Medium Blue is noticeably lighter, cooler than Prussian Blue Hue.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Medium Blue is noticeably lighter, cooler than Prussian Blue Hue.
The same difference applies the other way round: Prussian Blue Hue is noticeably darker, 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 Prussian Blue Hue on the colour wheel See Medium Blue on the colour wheel
All matches: Prussian Blue Hue equivalents · Medium Blue equivalents