Luminous Green INK vs Ink Green

How close are they?

ΔE 38.7, loose: different enough that you should pick on purpose. Ink Green is noticeably darker, much more muted, cooler than Luminous Green INK.

Can I use Ink Green instead of Luminous Green INK?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 39). Ink Green is noticeably darker, much more muted, cooler than Luminous Green INK.

Can I use Luminous Green INK instead of Ink Green?

The same difference applies the other way round: Luminous Green INK is noticeably lighter, much more saturated, 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.