Orange vs Blood Thorn

How close are they?

ΔE 15.6, loose: different enough that you should pick on purpose. Blood Thorn is a little darker, more saturated, cooler than Orange.

Can I use Blood Thorn instead of Orange?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Blood Thorn is a little darker, more saturated, cooler than Orange.

Can I use Orange instead of Blood Thorn?

The same difference applies the other way round: Orange is a little lighter, more muted, 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.