Fiery Vermilion vs Hot Orange

How close are they?

ΔE 9.4, close: similar, with a visible difference side by side. Hot Orange is a little lighter, more muted than Fiery Vermilion.

Can I use Hot Orange instead of Fiery Vermilion?

Usually, if you are not matching paint already on the model. Close match (ΔE 9). Hot Orange is a little lighter, more muted than Fiery Vermilion.

Can I use Fiery Vermilion instead of Hot Orange?

The same difference applies the other way round: Fiery Vermilion 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.