Phoenician Purple vs Eldandil Violet

How close are they?

ΔE 16.7, loose: different enough that you should pick on purpose. Eldandil Violet is a little darker, more muted, cooler than Phoenician Purple.

Can I use Eldandil Violet instead of Phoenician Purple?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Eldandil Violet is a little darker, more muted, cooler than Phoenician Purple.

Can I use Phoenician Purple instead of Eldandil Violet?

The same difference applies the other way round: Phoenician Purple is a little lighter, more saturated, warmer.

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.