ΔE 19.9, loose: different enough that you should pick on purpose. Anthraquinone Blue is much more saturated than Kantor Blue.
Can I use Anthraquinone Blue instead of Kantor Blue?
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 20). Anthraquinone Blue is much more saturated than Kantor Blue.
Can I use Kantor Blue instead of Anthraquinone Blue?
The same difference applies the other way round: Kantor Blue is 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.