Fluorescent Orange vs Vomit

How close are they?

ΔE 40.1, loose: different enough that you should pick on purpose. Vomit is noticeably lighter, much more muted than Fluorescent Orange.

Can I use Vomit instead of Fluorescent Orange?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 40). Vomit is noticeably lighter, much more muted than Fluorescent Orange.

Can I use Fluorescent Orange instead of Vomit?

The same difference applies the other way round: Fluorescent Orange is noticeably darker, much 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.