Hexed Violet vs Pastel Violet

How close are they?

ΔE 19.3, loose: different enough that you should pick on purpose. Pastel Violet is a little darker, much more saturated, warmer than Hexed Violet.

Can I use Pastel Violet instead of Hexed Violet?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Pastel Violet is a little darker, much more saturated, warmer than Hexed Violet.

Can I use Hexed Violet instead of Pastel Violet?

The same difference applies the other way round: Hexed Violet is a little lighter, much 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.