ΔE 25.9, loose: different enough that you should pick on purpose. Violet Vamp is noticeably darker, warmer than Cygnar Blue Highlight.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 26). Violet Vamp is noticeably darker, warmer than Cygnar Blue Highlight.
The same difference applies the other way round: Cygnar Blue Highlight is noticeably lighter, 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 Cygnar Blue Highlight on the colour wheel See Violet Vamp on the colour wheel
All matches: Cygnar Blue Highlight equivalents · Violet Vamp equivalents