Royal Purple vs Darth Blue

How close are they?

ΔE 20.5, loose: different enough that you should pick on purpose. Darth Blue is noticeably darker, much more muted, cooler than Royal Purple.

Can I use Darth Blue instead of Royal Purple?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 21). Darth Blue is noticeably darker, much more muted, cooler than Royal Purple.

Can I use Royal Purple instead of Darth Blue?

The same difference applies the other way round: Royal Purple is noticeably lighter, much 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.