Transparent Red Iron Oxide vs Orange Fire

How close are they?

ΔE 6.9, close: similar, with a visible difference side by side. Orange Fire is a little lighter, more saturated than Transparent Red Iron Oxide.

Can I use Orange Fire instead of Transparent Red Iron Oxide?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Orange Fire is a little lighter, more saturated than Transparent Red Iron Oxide.

Can I use Transparent Red Iron Oxide instead of Orange Fire?

The same difference applies the other way round: Transparent Red Iron Oxide is a little darker, more muted.

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.