Ruddy Fur vs Khaki Drill

How close are they?

ΔE 15.7, loose: different enough that you should pick on purpose. Khaki Drill is a little lighter, more muted than Ruddy Fur.

Can I use Khaki Drill instead of Ruddy Fur?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Khaki Drill is a little lighter, more muted than Ruddy Fur.

Can I use Ruddy Fur instead of Khaki Drill?

The same difference applies the other way round: Ruddy Fur is a little 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.