Vivid Volt vs Lemon Yellow

How close are they?

ΔE 20.5, loose: different enough that you should pick on purpose. Lemon Yellow is a little lighter, much more saturated, warmer than Vivid Volt.

Can I use Lemon Yellow instead of Vivid Volt?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 21). Lemon Yellow is a little lighter, much more saturated, warmer than Vivid Volt.

Can I use Vivid Volt instead of Lemon Yellow?

The same difference applies the other way round: Vivid Volt is a little darker, 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.