Algae Green vs Warp Lightning

How close are they?

ΔE 20.0, loose: different enough that you should pick on purpose. Warp Lightning is a little lighter, much more saturated than Algae Green.

Can I use Warp Lightning instead of Algae Green?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 20). Warp Lightning is a little lighter, much more saturated than Algae Green.

Can I use Algae Green instead of Warp Lightning?

The same difference applies the other way round: Algae Green is a little darker, much more muted.

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.