ΔE 19.2, loose: different enough that you should pick on purpose. Purple is a little darker, more saturated, warmer than Marine Blue.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Purple is a little darker, more saturated, warmer than Marine Blue.
The same difference applies the other way round: Marine Blue is a little 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 Marine Blue on the colour wheel See Purple on the colour wheel
All matches: Marine Blue equivalents · Purple equivalents