Fulgrim Pink vs Light Pink

How close are they?

ΔE 19.4, loose: different enough that you should pick on purpose. Light Pink is noticeably darker, much more saturated, warmer than Fulgrim Pink.

Can I use Light Pink instead of Fulgrim Pink?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Light Pink is noticeably darker, much more saturated, warmer than Fulgrim Pink.

Can I use Fulgrim Pink instead of Light Pink?

The same difference applies the other way round: Fulgrim Pink is noticeably lighter, much more muted, 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.