ΔE 19.6, loose: different enough that you should pick on purpose. Royal Purple is a little lighter, much more saturated than Corvus Black.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 20). Royal Purple is a little lighter, much more saturated than Corvus Black.
The same difference applies the other way round: Corvus Black is a little darker, much more muted.
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 Corvus Black on the colour wheel See Royal Purple on the colour wheel
All matches: Corvus Black equivalents · Royal Purple equivalents