ΔE 18.2, loose: different enough that you should pick on purpose. Light Yellow is a little darker, much more muted than Sun Yellow.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Light Yellow is a little darker, much more muted than Sun Yellow.
The same difference applies the other way round: Sun Yellow is a little lighter, much more saturated.
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.
See Sun Yellow on the colour wheel See Light Yellow on the colour wheel
All matches: Sun Yellow equivalents · Light Yellow equivalents