ΔE 19.4, loose: different enough that you should pick on purpose. USAF Light Gray is noticeably darker, more muted than Northern Flesh.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). USAF Light Gray is noticeably darker, more muted than Northern Flesh.
The same difference applies the other way round: Northern Flesh is noticeably lighter, 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 Northern Flesh on the colour wheel See USAF Light Gray on the colour wheel
All matches: Northern Flesh equivalents · USAF Light Gray equivalents