ΔE 22.4, loose: different enough that you should pick on purpose. Thornwood Green is much more muted, warmer than Guardian Green.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 22). Thornwood Green is much more muted, warmer than Guardian Green.
The same difference applies the other way round: Guardian Green is much 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 Guardian Green on the colour wheel See Thornwood Green on the colour wheel
All matches: Guardian Green equivalents · Thornwood Green equivalents