Dark Reaper vs Coal Black

How close are they?

ΔE 8.5, close: similar, with a visible difference side by side. Coal Black is a little lighter, more saturated than Dark Reaper.

Can I use Coal Black instead of Dark Reaper?

Usually, if you are not matching paint already on the model. Close match (ΔE 9). Coal Black is a little lighter, more saturated than Dark Reaper.

Can I use Dark Reaper instead of Coal Black?

The same difference applies the other way round: Dark Reaper is a little darker, 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.