Trollblood Base vs Scurvy Green

How close are they?

ΔE 18.5, loose: different enough that you should pick on purpose. Scurvy Green is noticeably darker, warmer than Trollblood Base.

Can I use Scurvy Green instead of Trollblood Base?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Scurvy Green is noticeably darker, warmer than Trollblood Base.

Can I use Trollblood Base instead of Scurvy Green?

The same difference applies the other way round: Trollblood Base is noticeably lighter, 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.