Beowulf Blue vs Shyish Purple

How close are they?

ΔE 15.8, loose: different enough that you should pick on purpose. Shyish Purple is a little lighter, warmer than Beowulf Blue.

Can I use Shyish Purple instead of Beowulf Blue?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Shyish Purple is a little lighter, warmer than Beowulf Blue.

Can I use Beowulf Blue instead of Shyish Purple?

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