British Camo Green vs Chromium Oxide Green Dark

How close are they?

ΔE 15.3, loose: different enough that you should pick on purpose. Chromium Oxide Green Dark is noticeably darker, cooler than British Camo Green.

Can I use Chromium Oxide Green Dark instead of British Camo Green?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Chromium Oxide Green Dark is noticeably darker, cooler than British Camo Green.

Can I use British Camo Green instead of Chromium Oxide Green Dark?

The same difference applies the other way round: British Camo Green is noticeably lighter, 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.