Metallic Green vs True Brass

How close are they?

ΔE 27.2, loose: different enough that you should pick on purpose. True Brass is a little darker, much more muted, warmer than Metallic Green.

Can I use True Brass instead of Metallic Green?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 27). True Brass is a little darker, much more muted, warmer than Metallic Green.

Can I use Metallic Green instead of True Brass?

The same difference applies the other way round: Metallic Green is a little lighter, 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.