ΔE 14.2, fair: the same colour family, but not a straight swap. Light Blue (Luftwaffe) is a little lighter, cooler than Light Feldgrau.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 14). Light Blue (Luftwaffe) is a little lighter, cooler than Light Feldgrau.
The same difference applies the other way round: Light Feldgrau is a little darker, 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 Light Feldgrau on the colour wheel See Light Blue (Luftwaffe) on the colour wheel
All matches: Light Feldgrau equivalents · Light Blue (Luftwaffe) equivalents