ΔE 7.4, close: similar, with a visible difference side by side. Naggaroth Night is a little lighter, more saturated than Broodmother Purple.
✓ Army Painter Fanatic conversion chart lists these two as equivalents.
Usually, if you are not matching paint already on the model. Close match (ΔE 7). Naggaroth Night is a little lighter, more saturated than Broodmother Purple.
The same difference applies the other way round: Broodmother Purple is a little darker, 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 Broodmother Purple on the colour wheel See Naggaroth Night on the colour wheel
All matches: Broodmother Purple equivalents · Naggaroth Night equivalents