ΔE 15.4, loose: different enough that you should pick on purpose. Abyss Blue is a little darker, much more muted, warmer than Thousand Sons Blue.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Abyss Blue is a little darker, much more muted, warmer than Thousand Sons Blue.
The same difference applies the other way round: Thousand Sons Blue is a little lighter, much more saturated, 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 Thousand Sons Blue on the colour wheel See Abyss Blue on the colour wheel
All matches: Thousand Sons Blue equivalents · Abyss Blue equivalents