Electric Lime vs Lemon Yellow

How close are they?

ΔE 21.2, loose: different enough that you should pick on purpose. Lemon Yellow is noticeably lighter, more saturated, warmer than Electric Lime.

Can I use Lemon Yellow instead of Electric Lime?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 21). Lemon Yellow is noticeably lighter, more saturated, warmer than Electric Lime.

Can I use Electric Lime instead of Lemon Yellow?

The same difference applies the other way round: Electric Lime is noticeably darker, 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.