Vermillion vs Squig Orange

How close are they?

ΔE 9.9, close: similar, with a visible difference side by side. Squig Orange is a little lighter, more saturated than Vermillion.

Can I use Squig Orange instead of Vermillion?

Usually, if you are not matching paint already on the model. Close match (ΔE 10). Squig Orange is a little lighter, more saturated than Vermillion.

Can I use Vermillion instead of Squig Orange?

The same difference applies the other way round: Vermillion 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.