ΔE 15.3, loose: different enough that you should pick on purpose. USAAF Light Gray is noticeably lighter than Cryx Bane Highlight.
Can I use USAAF Light Gray instead of Cryx Bane Highlight?
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). USAAF Light Gray is noticeably lighter than Cryx Bane Highlight.
Can I use Cryx Bane Highlight instead of USAAF Light Gray?
The same difference applies the other way round: Cryx Bane Highlight is noticeably darker.
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.