Rootpath vs US Field Drab

How close are they?

ΔE 8.3, close: similar, with a visible difference side by side. US Field Drab is a little lighter, more muted than Rootpath.

Can I use US Field Drab instead of Rootpath?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). US Field Drab is a little lighter, more muted than Rootpath.

Can I use Rootpath instead of US Field Drab?

The same difference applies the other way round: Rootpath 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.