ΔE 19.8, loose: different enough that you should pick on purpose. Dirty Grey is noticeably darker, more saturated, cooler than Khaki.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 20). Dirty Grey is noticeably darker, more saturated, cooler than Khaki.
The same difference applies the other way round: Khaki is noticeably 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 Khaki on the colour wheel See Dirty Grey on the colour wheel
All matches: Khaki equivalents · Dirty Grey equivalents