Barren Yellow vs Vulcan Orange

How close are they?

ΔE 7.2, close: similar, with a visible difference side by side. Vulcan Orange is warmer than Barren Yellow.

Can I use Vulcan Orange instead of Barren Yellow?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Vulcan Orange is warmer than Barren Yellow.

Can I use Barren Yellow instead of Vulcan Orange?

The same difference applies the other way round: Barren Yellow is cooler.

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.