Brownish Decay vs Khaki Drill

How close are they?

ΔE 20.2, loose: different enough that you should pick on purpose. Khaki Drill is noticeably lighter, more saturated, warmer than Brownish Decay.

Can I use Khaki Drill instead of Brownish Decay?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 20). Khaki Drill is noticeably lighter, more saturated, warmer than Brownish Decay.

Can I use Brownish Decay instead of Khaki Drill?

The same difference applies the other way round: Brownish Decay is noticeably darker, 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.