ΔE 14.9, fair: the same colour family, but not a straight swap. True Blue is a little darker, more saturated, cooler than Pale Indigo.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 15). True Blue is a little darker, more saturated, cooler than Pale Indigo.
The same difference applies the other way round: Pale Indigo is a little lighter, more muted, 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 Pale Indigo on the colour wheel See True Blue on the colour wheel
All matches: Pale Indigo equivalents · True Blue equivalents