ΔE 7.0, close: similar, with a visible difference side by side. Light Blue RLM78 is a little lighter, warmer than Gray FS36320.
Usually, if you are not matching paint already on the model. Close match (ΔE 7). Light Blue RLM78 is a little lighter, warmer than Gray FS36320.
The same difference applies the other way round: Gray FS36320 is a little darker, cooler.
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 Gray FS36320 on the colour wheel See Light Blue RLM78 on the colour wheel
All matches: Gray FS36320 equivalents · Light Blue RLM78 equivalents