Nuclear Sludge vs Bright Green

How close are they?

ΔE 18.3, loose: different enough that you should pick on purpose. Bright Green is noticeably darker, warmer than Nuclear Sludge.

Can I use Bright Green instead of Nuclear Sludge?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Bright Green is noticeably darker, warmer than Nuclear Sludge.

Can I use Nuclear Sludge instead of Bright Green?

The same difference applies the other way round: Nuclear Sludge is noticeably lighter, 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.