Mid Khaki Drill vs Sand Grey

How close are they?

ΔE 19.2, loose: different enough that you should pick on purpose. Sand Grey is noticeably lighter, much more muted than Mid Khaki Drill.

Can I use Sand Grey instead of Mid Khaki Drill?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Sand Grey is noticeably lighter, much more muted than Mid Khaki Drill.

Can I use Mid Khaki Drill instead of Sand Grey?

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