ΔE 20.4, loose: different enough that you should pick on purpose. Khaki Drill is noticeably darker, more muted than Drain Life.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 20). Khaki Drill is noticeably darker, more muted than Drain Life.
The same difference applies the other way round: Drain Life 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 Drain Life on the colour wheel See Khaki Drill on the colour wheel
All matches: Drain Life equivalents · Khaki Drill equivalents