True Blue vs Russian AF Blue

How close are they?

ΔE 18.7, loose: different enough that you should pick on purpose. Russian AF Blue is noticeably lighter, more muted, cooler than True Blue.

Can I use Russian AF Blue instead of True Blue?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Russian AF Blue is noticeably lighter, more muted, cooler than True Blue.

Can I use True Blue instead of Russian AF Blue?

The same difference applies the other way round: True Blue is noticeably darker, 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.