Dark Olive vs Raw Umber

How close are they?

ΔE 7.8, close: similar, with a visible difference side by side. Raw Umber is a little lighter, more saturated than Dark Olive.

Can I use Raw Umber instead of Dark Olive?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). Raw Umber is a little lighter, more saturated than Dark Olive.

Can I use Dark Olive instead of Raw Umber?

The same difference applies the other way round: Dark Olive is a little darker, more muted.

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.