Iceborn vs Frostbite

How close are they?

ΔE 15.1, loose: different enough that you should pick on purpose. Frostbite is a little lighter, more muted than Iceborn.

Can I use Frostbite instead of Iceborn?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Frostbite is a little lighter, more muted than Iceborn.

Can I use Iceborn instead of Frostbite?

The same difference applies the other way round: Iceborn is a little 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.