ΔE 28.6, loose: different enough that you should pick on purpose. Lemon Yellow is noticeably lighter, much more saturated, warmer than Army Green.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 29). Lemon Yellow is noticeably lighter, much more saturated, warmer than Army Green.
The same difference applies the other way round: Army Green is noticeably darker, much more muted, cooler.
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 Army Green on the colour wheel See Lemon Yellow on the colour wheel
All matches: Army Green equivalents · Lemon Yellow equivalents