ΔE 14.7, fair: the same colour family, but not a straight swap. RLM 78 Light Blue is noticeably darker, cooler than Ice Storm.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 15). RLM 78 Light Blue is noticeably darker, cooler than Ice Storm.
The same difference applies the other way round: Ice Storm is noticeably lighter, warmer.
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.
See Ice Storm on the colour wheel See RLM 78 Light Blue on the colour wheel
All matches: Ice Storm equivalents · RLM 78 Light Blue equivalents