ΔE 16.8, loose: different enough that you should pick on purpose. Russian AF Blue is a little darker, much more muted, cooler than Light Blue.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Russian AF Blue is a little darker, much more muted, cooler than Light Blue.
The same difference applies the other way round: Light Blue is a little lighter, much more saturated, 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 Blue on the colour wheel See Russian AF Blue on the colour wheel
All matches: Light Blue equivalents · Russian AF Blue equivalents