Wyldwood vs Demon Brown

How close are they?

ΔE 16.4, loose: different enough that you should pick on purpose. Demon Brown is a little lighter, much more saturated, cooler than Wyldwood.

Can I use Demon Brown instead of Wyldwood?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Demon Brown is a little lighter, much more saturated, cooler than Wyldwood.

Can I use Wyldwood instead of Demon Brown?

The same difference applies the other way round: Wyldwood is a little darker, much more muted, warmer.

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.