Slaughter Red vs Baal Red

How close are they?

ΔE 20.5, loose: different enough that you should pick on purpose. Baal Red is a little lighter, much more saturated than Slaughter Red.

Can I use Baal Red instead of Slaughter Red?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 21). Baal Red is a little lighter, much more saturated than Slaughter Red.

Can I use Slaughter Red instead of Baal Red?

The same difference applies the other way round: Slaughter Red is a little darker, much more muted.

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.