Ogre Brown vs Khaki Drill

How close are they?

ΔE 23.8, loose: different enough that you should pick on purpose. Khaki Drill is a little darker, much more muted than Ogre Brown.

Can I use Khaki Drill instead of Ogre Brown?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 24). Khaki Drill is a little darker, much more muted than Ogre Brown.

Can I use Ogre Brown instead of Khaki Drill?

The same difference applies the other way round: Ogre Brown is a little lighter, 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.