Shamrock Green vs Troll Green

How close are they?

ΔE 49.7, loose: different enough that you should pick on purpose. Troll Green is noticeably darker, much more muted, cooler than Shamrock Green.

Can I use Troll Green instead of Shamrock Green?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 50). Troll Green is noticeably darker, much more muted, cooler than Shamrock Green.

Can I use Shamrock Green instead of Troll Green?

The same difference applies the other way round: Shamrock Green is noticeably lighter, much 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.