Radiant Platinum vs Arctic Blue (Metal.)

How close are they?

ΔE 23.2, loose: different enough that you should pick on purpose. Arctic Blue (Metal.) is noticeably lighter, more muted than Radiant Platinum.

Can I use Arctic Blue (Metal.) instead of Radiant Platinum?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 23). Arctic Blue (Metal.) is noticeably lighter, more muted than Radiant Platinum.

Can I use Radiant Platinum instead of Arctic Blue (Metal.)?

The same difference applies the other way round: Radiant Platinum is noticeably darker, more saturated.

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.