ΔE 28.6, loose: different enough that you should pick on purpose. Metallic Blue Green is much more saturated than Broadsword Silver.
Can I use Metallic Blue Green instead of Broadsword Silver?
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 29). Metallic Blue Green is much more saturated than Broadsword Silver.
Can I use Broadsword Silver instead of Metallic Blue Green?
The same difference applies the other way round: Broadsword Silver is 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.