Mid Khaki Drill vs Cloudy Sky

How close are they?

ΔE 20.7, loose: different enough that you should pick on purpose. Cloudy Sky is noticeably lighter, more muted than Mid Khaki Drill.

Can I use Cloudy Sky instead of Mid Khaki Drill?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 21). Cloudy Sky is noticeably lighter, more muted than Mid Khaki Drill.

Can I use Mid Khaki Drill instead of Cloudy Sky?

The same difference applies the other way round: Mid Khaki Drill is noticeably darker, 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.