Purple Alchemy vs Velvet Red

How close are they?

ΔE 27.1, loose: different enough that you should pick on purpose. Velvet Red is noticeably darker, much more muted, warmer than Purple Alchemy.

Can I use Velvet Red instead of Purple Alchemy?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 27). Velvet Red is noticeably darker, much more muted, warmer than Purple Alchemy.

Can I use Purple Alchemy instead of Velvet Red?

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