Sunpetal vs Lemon Yellow

How close are they?

ΔE 15.2, loose: different enough that you should pick on purpose. Lemon Yellow is a little darker, more muted, cooler than Sunpetal.

Can I use Lemon Yellow instead of Sunpetal?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Lemon Yellow is a little darker, more muted, cooler than Sunpetal.

Can I use Sunpetal instead of Lemon Yellow?

The same difference applies the other way round: Sunpetal is a little lighter, 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.