ΔE 35.4, loose: different enough that you should pick on purpose. Dragon Blue is noticeably darker, much more muted, warmer than Phantasmal Blue.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 35). Dragon Blue is noticeably darker, much more muted, warmer than Phantasmal Blue.
The same difference applies the other way round: Phantasmal Blue is noticeably 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 Phantasmal Blue on the colour wheel See Dragon Blue on the colour wheel
All matches: Phantasmal Blue equivalents · Dragon Blue equivalents