Patagon Pine vs Viridian Green

How close are they?

ΔE 19.2, loose: different enough that you should pick on purpose. Viridian Green is much more saturated, cooler than Patagon Pine.

Can I use Viridian Green instead of Patagon Pine?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Viridian Green is much more saturated, cooler than Patagon Pine.

Can I use Patagon Pine instead of Viridian Green?

The same difference applies the other way round: Patagon Pine is much more muted, 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.