Molten Orange vs Flat Earth

How close are they?

ΔE 9.5, close: similar, with a visible difference side by side. Flat Earth is a little lighter, more muted than Molten Orange.

Can I use Flat Earth instead of Molten Orange?

Usually, if you are not matching paint already on the model. Close match (ΔE 10). Flat Earth is a little lighter, more muted than Molten Orange.

Can I use Molten Orange instead of Flat Earth?

The same difference applies the other way round: Molten Orange 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.