ΔE 6.3, close: similar, with a visible difference side by side. Field Blue is a little lighter, more muted than Engine Gray FS16081.
Usually, if you are not matching paint already on the model. Close match (ΔE 6). Field Blue is a little lighter, more muted than Engine Gray FS16081.
The same difference applies the other way round: Engine Gray FS16081 is a little darker, more saturated.
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 Engine Gray FS16081 on the colour wheel See Field Blue on the colour wheel
All matches: Engine Gray FS16081 equivalents · Field Blue equivalents