ΔE 17.8, loose: different enough that you should pick on purpose. Buff is more muted, cooler than Yellow Ochre.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Buff is more muted, cooler than Yellow Ochre.
The same difference applies the other way round: Yellow Ochre is 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.
See Yellow Ochre on the colour wheel See Buff on the colour wheel
All matches: Yellow Ochre equivalents · Buff equivalents