ΔE 12.1, fair: the same colour family, but not a straight swap. Purple Black is a little lighter, more muted than Terrestrial Titan.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Purple Black is a little lighter, more muted than Terrestrial Titan.
The same difference applies the other way round: Terrestrial Titan is a little darker, more saturated.
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 Terrestrial Titan on the colour wheel See Purple Black on the colour wheel
All matches: Terrestrial Titan equivalents · Purple Black equivalents