Wyldwood vs Desert Ochre

How close are they?

ΔE 19.2, loose: different enough that you should pick on purpose. Desert Ochre is noticeably lighter, much more saturated than Wyldwood.

Can I use Desert Ochre instead of Wyldwood?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Desert Ochre is noticeably lighter, much more saturated than Wyldwood.

Can I use Wyldwood instead of Desert Ochre?

The same difference applies the other way round: Wyldwood is noticeably darker, much 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.