ΔE 16.4, loose: different enough that you should pick on purpose. Off-White is noticeably darker, more muted, warmer than Pastel Yellow.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Off-White is noticeably darker, more muted, warmer than Pastel Yellow.
The same difference applies the other way round: Pastel Yellow is noticeably lighter, more saturated, 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.
See Pastel Yellow on the colour wheel See Off-White on the colour wheel
All matches: Pastel Yellow equivalents · Off-White equivalents