Blue Gorkshroom vs Violet

How close are they?

ΔE 15.8, loose: different enough that you should pick on purpose. Violet is a little lighter, much more muted, warmer than Blue Gorkshroom.

Can I use Violet instead of Blue Gorkshroom?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Violet is a little lighter, much more muted, warmer than Blue Gorkshroom.

Can I use Blue Gorkshroom instead of Violet?

The same difference applies the other way round: Blue Gorkshroom is a little darker, 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.