ΔE 9.0, close: similar, with a visible difference side by side. Pyrrole Red Dark is a little darker, more muted than Fiery Vermilion.
Usually, if you are not matching paint already on the model. Close match (ΔE 9). Pyrrole Red Dark is a little darker, more muted than Fiery Vermilion.
The same difference applies the other way round: Fiery Vermilion is a little lighter, 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.
See Fiery Vermilion on the colour wheel See Pyrrole Red Dark on the colour wheel
All matches: Fiery Vermilion equivalents · Pyrrole Red Dark equivalents