ΔE 15.4, loose: different enough that you should pick on purpose. Buff is a little lighter, more muted, warmer than Interior Green.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Buff is a little lighter, more muted, warmer than Interior Green.
The same difference applies the other way round: Interior Green is a little darker, 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 Interior Green on the colour wheel See Buff on the colour wheel
All matches: Interior Green equivalents · Buff equivalents