ΔE 12.4, fair: the same colour family, but not a straight swap. Sky Blue is noticeably lighter than Imrik Blue.
Can I use Sky Blue instead of Imrik Blue?
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Sky Blue is noticeably lighter than Imrik Blue.
Can I use Imrik Blue instead of Sky Blue?
The same difference applies the other way round: Imrik Blue is noticeably darker.
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.