Flag Red vs Carnage Red

How close are they?

ΔE 7.1, close: similar, with a visible difference side by side. Carnage Red is a little lighter, more muted than Flag Red.

Can I use Carnage Red instead of Flag Red?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Carnage Red is a little lighter, more muted than Flag Red.

Can I use Flag Red instead of Carnage Red?

The same difference applies the other way round: Flag Red is a little darker, more saturated.

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.