ΔE 7.7, close: similar, with a visible difference side by side. Light Blue RLM65 is a little darker, more saturated than Light Gray (IJA).
Usually, if you are not matching paint already on the model. Close match (ΔE 8). Light Blue RLM65 is a little darker, more saturated than Light Gray (IJA).
The same difference applies the other way round: Light Gray (IJA) is a little lighter, more muted.
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 Light Gray (IJA) on the colour wheel See Light Blue RLM65 on the colour wheel
All matches: Light Gray (IJA) equivalents · Light Blue RLM65 equivalents