Fluor Yellow-Orange vs Vomit

How close are they?

ΔE 29.5, loose: different enough that you should pick on purpose. Vomit is much more saturated, cooler than Fluor Yellow-Orange.

Can I use Vomit instead of Fluor Yellow-Orange?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 29). Vomit is much more saturated, cooler than Fluor Yellow-Orange.

Can I use Fluor Yellow-Orange instead of Vomit?

The same difference applies the other way round: Fluor Yellow-Orange is much more muted, warmer.

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.