ΔE 7.8, close: similar, with a visible difference side by side. Flanker Blue is a little darker, more saturated, cooler than Medium Sea Gray (RAF).
Usually, if you are not matching paint already on the model. Close match (ΔE 8). Flanker Blue is a little darker, more saturated, cooler than Medium Sea Gray (RAF).
The same difference applies the other way round: Medium Sea Gray (RAF) is a little lighter, more muted, 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 Medium Sea Gray (RAF) on the colour wheel See Flanker Blue on the colour wheel
All matches: Medium Sea Gray (RAF) equivalents · Flanker Blue equivalents