Iron Warriors vs Metallic Blue Green

How close are they?

ΔE 26.6, loose: different enough that you should pick on purpose. Metallic Blue Green is a little lighter, much more saturated than Iron Warriors.

Can I use Metallic Blue Green instead of Iron Warriors?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 27). Metallic Blue Green is a little lighter, much more saturated than Iron Warriors.

Can I use Iron Warriors instead of Metallic Blue Green?

The same difference applies the other way round: Iron Warriors is a little darker, much more muted.

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.