Legendary Red vs Naphthol Red Medium

How close are they?

ΔE 9.4, close: similar, with a visible difference side by side. Naphthol Red Medium is a little darker than Legendary Red.

Can I use Naphthol Red Medium instead of Legendary Red?

Usually, if you are not matching paint already on the model. Close match (ΔE 9). Naphthol Red Medium is a little darker than Legendary Red.

Can I use Legendary Red instead of Naphthol Red Medium?

The same difference applies the other way round: Legendary Red is a little lighter.

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.