Violet Grey vs Light Violet

How close are they?

ΔE 18.7, loose: different enough that you should pick on purpose. Light Violet is a little lighter, more saturated, warmer than Violet Grey.

Can I use Light Violet instead of Violet Grey?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Light Violet is a little lighter, more saturated, warmer than Violet Grey.

Can I use Violet Grey instead of Light Violet?

The same difference applies the other way round: Violet Grey is a little darker, more muted, 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.