ΔE 18.5, loose: different enough that you should pick on purpose. Light Violet is noticeably darker, more saturated than Light Lavender.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Light Violet is noticeably darker, more saturated than Light Lavender.
The same difference applies the other way round: Light Lavender is noticeably lighter, 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.
See Light Lavender on the colour wheel See Light Violet on the colour wheel
All matches: Light Lavender equivalents · Light Violet equivalents